On January 5, 1991, the Baggies hosted non-league Woking at The Hawthorns in the third round of the world's oldest knockout competition.
Manager Brian Talbot had recently added an up-and-coming coach by the name of Sam Allardyce to his staff.
But while Albion were struggling in the old Second Division at the time, they were still expected to blow away the minnows from Surrey.
Instead, the distinctively named Tim Buzaglo wrote his name into the history books of both clubs by scoring a stunning hat-trick and earning an incredible 4-2 win for the Cards.
Today, just over 20-years on, Albion will travel to the Kingfield Stadium to commemorate that match.
The friendly fixture will be the first time Baggies fans get to see their side under new boss Valerien Ismael.
But while the initial cup-tie took place over two decades ago, Albion favourite Bernie McNally, who played in midfield that day, can remember it like it was yesterday.
"That was one of the worst games I played in – it was horrible," he said.
"We actually took the lead but then you could just sense it wasn't going to be our day, I could feel the game slipping away.
"It was one of those games where – with 20 minutes to go – I was thinking I wouldn't mind getting an injury here and coming off. It was awful.
"And their striker – Buzaglo – took full advantage.
"You see FA Cup shocks every season. And whenever one happens I am taken back to that day. We really were dreadful.
"The game was horrible to play in and it was horrible when we came off.
"I remember someone throwing a bin bag full of rubbish at us and rightly so because we had been an embarrassment.
"I honestly wish I could say I spent that game sat in the stands. But I didn't, I have to hold my hands up and say I played in it.
"Sometimes you get those days in football, but it really was one of the worst games I played in."
It was Colin West who had initially put Albion ahead in the match.
But a stunning second-half comeback turned the tie on its head as Buzaglo netted his treble in the space of 15 minutes before Terry Worsfold made it 4-1.
A consolation goal from Albion's Darren Bradley wasn't enough – with Woking going on to face Everton in the fourth round a few weeks later, where they fell to a narrow 1-0 defeat.
Following the defeat to Woking, Talbot and Allardyce were sacked.
"Sam Allardyce was just starting out as a coach at that time," McNally added.
"But when we got in the dressing room, Brian said we had put the final nail in his coffin.
"As a manager, there is no coming back from a defeat like that. The writing was on the wall.
"That day sealed his fate but as players, we have to take responsibility for that defeat. We really let him down."