Ollie Norburn’s fourth minute penalty was in vain as Lankaster condemned Shrewsbury to more stoppage time misery, following on from being pegged back by Swindon last weekend, and further cranked up the pressure on Ricketts.
Salop were 15 minutes from a famous first ever win in 13 attempts at Portman Road but Ethan Ebanks-Landell shanked in an own goal with 15 minutes left before sub Lankester stooped to nod in a rebound off keeper Harry Burgoyne seven minutes into seven added on.
Shrewsbury are now seven without a win in League One this season and remain 22nd. They have won just one from their first 12 league games this season.
Another late collapse, as Ipswich remain third and extend their perfect home league record to six wins from six, leaves Town supporters watching on at home infuriated.
Town are four points adrift of the sides above them and Ricketts’ future is likely to hang in the balance with big sections of the support calling for change.
An open, watchable game could have gone either way but, after defending well for the majority of the contest, sloppy Shrewsbury switched off late on and were punished.
It was a game of penalties that were given and were turned away. Norburn converted Shrewsbury’s first of the season and they could have had a couple more throughout the contest, while Paul Lambert’s Ipswich also had appeals.
But it was no hard luck story for Salop whose punishing campaign extends as the pressure continues to grow.
Ricketts named an unchanged Shrewsbury team for the first time this season at the 12th time of asking in League One and 17th in all competitions.
It had been Town’s first free midweek since the end of September and start of October, and the Shrews boss had been grateful for the chance to get some minutes on the Sundorne Castle training pitch into his players.
Harry Burgoyne kept his place between the sticks from the 3-3 draw against Swindon seven days earlier for the visitors, despite Ricketts revealing Arsenal loan goalkeeper Deyan Iliev was fit again after injury.
Salop remained without a natural centre-forward in their starting line-up, with Shaun Whalley - making his 199th appearance for the club at the stadium he was sent off in last season - Marc Pugh and Shilow Tracey the front three.
Like against Swindon, Pugh was the option as the ‘false nine’ striker from the off.
Ricketts resisted the opportunity to change his midfield two, with Josh Vela returning from a three-match ban. Ryan Barnett got the nod over the likes of Josh Daniels and Jan Zamburek for a place on the bench.
Town knew they were battling history against Ipswich. Shrewsbury had won just one of 17 league meetings between the two, coming in January 1987. Shrews were winless at Portman Road, taking just a point for their troubles.
There were familiar faces in the Tractor Boys line-up. Jon Nolan and Toto Nsiala, two of Paul Hurst’s heroes in the Shrews side that made the play-off final three seasons ago, both started for the hosts.
Hurst subsequently brought the pair with him after swapping Shropshire for Suffolk.
Paul Lambert’s side boasted a perfect home League One record ahead of kick-off. The Suffolk side had won five from five, scoring eight without reply. They were braced for a big week of home games against Shrews, Hull and Charlton inside seven days.
Shrewsbury were encouraged by the surprise omission of talented attacker Gwion Edwards from Ipswich’s line-up, but there was a place for striker Kayden Jackson, whose season has been broken up by injury. He scored in the 3-0 win in this fixture last season, one of 11 goals last term.
It was a first league in 18 days for Ipswich, their last outing in league action a 2-1 defeat at Sunderland, but Lambert’s men had been peerless at home this season, dispatching Wigan, Rochdale, Accrington, Gillingham and Crewe.
Salop, by contrast, were six without a win in the league but had gone unbeaten in four in the league, with wins coming in the FA Cup and EFL Trophy. Positive league results were needed to stop the rot and improve on their alarming position.
Shrewsbury were hopeful of a sluggish start from their hosts after an enforced league break.
And Ricketts’ men started brilliantly. A lofted pass from captain Norburn caught out the entire Ipswich defence and had Whalley darting towards the home penalty box from the right.
He was trailed by Mark McGuinness, who could not keep up and clipped Whalley’s heels inside the box. It was a clear penalty after just three minutes.
Norburn took responsibility for Town’s first penalty of the season, drilling down the middle via a faint touch off keeper Tomas Holy, but there was no stopping the strike. Shrewsbury’s first league goal at Ipswich since netting in a 5-1 defeat in 1957.
Ipswich’s record of shutouts at their own stadium was done after barely 200 seconds and Salop sensed the chance was there to go for the jugular while the hosts woke from their slumber.
The lead could’ve been doubled inside 10 minutes as Whalley opted to try to find Shilow Tracey instead of letting fly himself after the lively visitors broke two on two.
A low strike from the edge of the box by Jackson was Burgoyne’s first involvement of note but Shrewsbury were setting the tempo, with the front three tireless and Norburn winning the ball in midfield.
The visitors were left hopping mad with rage on 16 minutes. A move worked its way to Pugh on the left side of the home box. The Town flyer checked inside cleverly, leaving Holy and McGuinness for dead, but a trailing leg from the defending caught Pugh and the Shrews man hit the deck.
Shrewsbury appeals could not have been louder. The entire dugout hopped almost on to the pitch demanding another penalty. Referee Tim Robinson was unmoved. Town looked to have been denied a stonewall spot-kick, and Ricketts reserved some choice words from the officials, calling them a disgrace.
Supporters watching at home on iFollow, with the benefit of a replay, felt the decision was not as clear-cut as it appeared live.
Just as against Swindon a week earlier, Shrewsbury had started very well. They were further encouraged when Nolan limped off 20 minutes in, meaning his reunion was cut short.
Shrews’ Matt Millar was busy down the right flank, with a couple of decent deliveries as he linked well with Whalley and Pugh.
Tracey was an honest and willing runner down the left, stretching a cautious Ipswich backline with his pace.
Not for the first time this season, Ipswich could be accused of wanting too much time in midfield. Town were working tirelessly out of possession to ensure they could not settle.
Teddy Bishop, a goal threat from midfield, brought a routine save from Burgoyne with a pot-shot on half hour but Lambert’s men were struggling to create anything clear-cut inside the visitors’ box.
Shrewsbury’s backline had taken its fair share of criticism in recent weeks but they were standing up to the task in Suffolk. Aaron Pierre made a key interception to the tune of audible encouragement from colleagues Ethan Ebanks-Landell and Ro-Shaun Williams.
And the defence had to be at their best to keep out Ipswich’s best effort, on 38 minutes.
The Tractor Boys’ first bit of incisive play saw Jackson released to the right byline, his low cut-back was perfect for sub Jack Lankester but Ebanks-Landell made a superb block almost from his own goalline. The rebound fell to Freddie Sears but a haul of bodies somehow made another block.
Ipswich were guilty of not being ruthless from close range but it was excellent defending.
The closest moments of the first period, which was extended due to a couple of injury stoppages, had the home side in charge of the ball but posing few tough questions to their visitors.
Shrews’ attacking threat from the opening 20 minutes had died down, but Ricketts’ men were still lively on the break. The home side appealed for a spot-kick of their own just before the break as Williams shoved Nsiala from a corner but calls fell on deaf ears.
Crucially, Ricketts’ side went in at the break without Ipswich chinking their armour.
But Salop’s lead was almost cancelled out barely 60 seconds after the restarts. A nice ball over Shrews’ defence played Jackson in on goal.
The striker tried to lift a bouncing ball over the onrushing Burgoyne, but the keeper made a big stop as the ball pinballed behind, Burgoyne caught Jackson after making the save but shouts were once more ignored.
Ipswich’s difficult afternoon went from bad to worse five minutes into the second period as the influential Bishop limped off injured. Lambert welcomed the rule change to permit five substitutes as his list of absentees continued to grow.
There was very little between the sides as the clock ticked past the hour. Ricketts’ visitors were doing enough, holding Ipswich at arm’s length. The hosts were not doing nearly enough to stretch Salop.
Tracey remained a lively outball for Shrews, his pace posing a threat to tiring Ipswich bodies.
Ipswich made some club history with their third and fourth substitutions as the second half neared its midway point. Shrews were yet to make a change.
And the Tractor Boys passed up another golden chance to draw level with some more poor finishing.
Lovely skill from Sears worked the space with a nutmeg and his low cross was scuffed to the back post, where a sliding Judge forced it goalwards, only for the giant frame of Burgoyne sprawling across his goalline to help somehow keep the ball out. Bodies thudded against the post in a messy melee.
Ipswich had the best opportunities but Salop could have put the contest to bed. A sharp Pugh strike from the edge of the box was straight down the throat of Holy in goal.
Moments later, Whalley and Pugh worked an opening but the latter could not make the most of his encouraging position in the box.
Town’s resolve was finally undone with 15 minutes remaining and in frustrating style.
Home sub Keanen Bennetts delivered from the right and, under little pressure, Ebanks-Landell shanked a first-time volleyed clearance with his weaker left foot but got it all wrong, the ball sliding in the wrong direction and in across the unfortunate Burgoyne’s goal. The keeper could do nothing on this occasion.
Ricketts responded by sending on Vela, Barnett and Daniel Udoh as the visitors went about protecting their point while hoping to push on and regain the lead. Udoh was lively in the frontline as was Barnett.
The youngster caught the half-asleep Nsiala and crossed for Udoh but some good defending kept Town out. Ipswich remained ropey at the back.
Home skipper Luke Chambers sent a near post header from a corner wide before sub Bennetts header over under pressure from the Shrews defence. Williams reserved some choice words towards his own dugout.
Seven minutes were added on with the contest on a knife-edge. Sloppy Ipswich were almost punished as Barnett and Udoh won the ball and broke two on two again, Barnett darted into the box against Nsiala and appeared to be brought down but quiet Shrews appeals were waved away.
Ricketts introduced Brad Walker for Pugh late on as the midfielder became Shrewsbury's first ever fourth substitute in a league fixture.
It felt like Town may have done enough for the point but it wasn’t to be.
A shot from Judge was parried by Burgoyne straight into the path of Lankester who duly obliged heading in from six yards. It was not the finest piece of goalkeeping.
It could’ve change further still as Ebanks-Landell missed a great chance to dramatically make it 2-2 but Town were left empty handed with only themselves to blame.
A third time in 12 League One games this season that Shrewsbury have been denied in added time as pressure grows.
Ipswich Town (4-3-3):
Holy; Chambers, Nsiala, McGuinness, Ward; Nolan (Lankester, 22), McGavin, Bishop (Huws, 50); Sears (Bennetts, 66), Judge, Jackson (Norwood, 66).
Subs not used: Cornell (gk). Woolfenden, Kenlock.
Shrewsbury Town (3-4-3):
Burgoyne; Williams, Ebanks-Landell, Pierre; Millar, Edwards, Norburn © (Vela, 76), C Daniels; Tracey (Barnett, 79), Pugh (Walker, 89), Whalley (Udoh, 79).
Subs not used: Iliev (gk), High, Cummings.
Referee: Tim Robinson