With Manchester United 3-2 down and edging towards what would be another hugely damaging defeat for Erik ten Hag, their under-pressure manager decided it was time to turn to his bench.

Who did he think could grab his side a late equaliser? Which player could become his Mark Robins?

As the clock ticked towards 80 minutes, Ten Hag's answer was both unexpected and unconventional.

Off came centre-halves Lisandro Martinez and Matthijs de Ligt and on came... centre-halves Jonny Evans and Harry Maguire.

"This is the strangest substitution," said former England goalkeeper Paul Robinson on BBC Radio 5 Live when the board went up. "Manchester United are chasing a game with 12 minutes to go!"

There were plenty of you getting in touch with us to share the same sentiments, too...

Mike: Really Ten Hag??? 3-2 down and you bring on two defenders... you playing for your P45???

Kevan: Ludicrous. Ten Hag just shows no management sense at all. Two defenders come on as subs for two other defenders.

GG: Subbing on Maguire & Evans when a goal down & 10 minutes left. Is Ten Hag actively trying to get sacked??!!

Did Ten Hag know something the rest of us didn't?

"We said, 'why was he bringing on Maguire and Evans?' That's why."

Those were the words of Robinson moments after England defender Maguire met Christian Eriksen's 91st-minute corner to send a thumping header beyond Porto goalkeeper Diogo Costa.

It was 3-3. Relief for Ten Hag and United's supporters, who had also seen captain Bruno Fernandes sent off for the second time in five days just three minutes after Maguire and Evans had come on.

David: Has Harry Maguire just saved Erik ten (man's) Hag's job?

Scott: Ten Hag saved by the man he stripped the captaincy from and has tried to sell for two years!

Seb: I think Maguire has just kept Ten Hag in a job. Another questionable performance from Manchester United.

Maguire himself admitted that, despite his late rescue act, there were parts of United's display that were indeed questionable.

"When you get 2-0 away from home you have to be a little bit more solid and there were far too many gaps," the England international told TNT Sport.

"It's something we need to improve. If we want to be successful this season we can't keep conceding two goals."

Alejandro Garnacho had already been introduced at half-time in place of Marcus Rashford, itself a surprising change after the 26-year-old had scored one and made another during the first 45 minutes.

The United boss said that switch was purely to “rotate” his squad before facing Aston Villa on Sunday.

It did, however, leave him relatively short of attacking moves to make in the second period, with winger Antony and forward Joshua Zirkzee also having been brought on in a double switch 10 minutes prior to Maguire and Evans.

By the time the centre-half duo were preparing to enter the field, the visitors were left with 20-year-old midfielder Daniel Gore as one option, with only two previous substitute appearances to his name, plus the more defensive-minded Manuel Ugarte and Toby Collyer.

Defender Victor Lindelof and back-up goalkeepers Tom Heaton and Altay Bayindir were the only other players on the bench so, unless Ten Hag was planning a sensational David James-style substitution, he wasn't spoilt for choice.

Substitutes are becoming a bigger and bigger part of the game, especially with five changes allowed - half of a team's outfield players.

The Premier League has seen more substitute goals this season than ever before, with the previous record set last season.

Aston Villa striker Jhon Duran, alone, has scored five goals off the bench in all competitions this term, with four of them winning goals - most notably his long-range strike in their 1-0 Champions League win over Bayern Munich on Wednesday.

Tottenham, Scottish side Hearts and Irish champions Shamrock Rovers all benefited from big substitute goals in Thursday's European games.

Brennan Johnson netted a crucial late Europa League for Tottenham in their 2-1 win over Ferencvaros.

Yan Dhanda scored a 94th-minute winner against Dinamo Minsk in the Conference League, while Dylan Watts netted an injury-time equaliser for Shamrock Rovers against APOEL.

The trend has even spread to international football, with eight subs scoring winning goals at Euro 2024 - including Spain's Mikel Oyarzabal in the final against England.