Explained: Why new Wolves striker Adam Armstrong is eligible for Wolves FA Cup clash with Grimsby Town

Armstrong, who made a deadline-day switch from Southampton in a deal worth up to £9 million, would previously have been cup-tied after already featuring in the competition.

The 29-year-old came on as an 87th-minute substitute in Southampton's 3-2 win over Doncaster in the third round of the FA Cup last month.

Under previous regulations, Armstrong would have been ineligible for Wolves' fourth-round tie at League Two side Grimsby Town, as players were only permitted to represent one club per season in the competition proper.

However, the Football Association has relaxed its rules. The updated cup-tied rule now specifies that players are permitted to play for two clubs in the FA Cup in the same season.

It reads: "A player is now permitted to play for TWO clubs in the competition in the same season.

"One club in the qualifying competition and another club in the competition proper, or two clubs in the competition proper."

Similar changes have also been introduced in the Carabao Cup this season.

Armstrong made a bright start to life at Wolves, registering an assist on his debut in the defeat to Chelsea at Molineux.

The forward began on the left against Chelsea before moving into a more central role following a tactical reshuffle, linking up with Tolu Arokodare and providing the assist for Wolves' goal.

The 29-year-old has been signed with next season in mind, amid expectations that Wolves could face relegation from the Premier League.

His contribution against Chelsea took Armstrong's top-flight tally to six goals and eight assists in 90 appearances. However, his Championship record is considerably stronger, with 91 goals and 37 assists in 277 matches.

Wolves boss Rob Edwards said the striker is "hungry" to prove people wrong and demonstrate he can succeed at Premier League level.

He added that he has admired Armstrong for a "long, long time" and is delighted the forward chose to join the Old Gold.