Jordan Ayew’s late winner put Crystal Palace into the FA Cup fourth round as they finally broke down a resolute Grimsby, who played with 10 men for almost the entire match.
Left-back Andrew Fox was sent off in the second minute for a high challenge on Andros Townsend, after the input of the video assistant referee.
Palace had 33 attempts on goal in the game, only to be repelled by League Two Grimsby’s fine defence, but substitute Ayew rose to head in Jeffrey Schlupp’s free-kick in the 86th minute.
The result was harsh on Grimsby, who looked on course to take their Premier League opponents to a deserved replay.
This was another worrying performance for a Palace side who have struggled to score this season, but they will be relieved their onslaught eventually edged them through at Selhurst Park.
Gutsy Grimsby and profligate Palace
Fox was dismissed after catching Palace winger Townsend on the shin with his studs up. Referee Martin Atkinson originally showed a yellow card before VAR intervened to overturn it to a straight red.
It ensured the rest of the game was effectively attack against defence – a daunting challenge that Grimsby met with fine organisation and tremendous resolve.
Reece-Hall Johnson made several vital interceptions, including clearing Alexander Sorloth’s header off the line, and, with fellow defenders Mitch Rose and Luke Hendrie, helped his side keep their shape superbly to frustrate Palace.
Townsend went close with either foot in the second half, while Grimsby goalkeeper James McKeown made a fine diving save from Sorloth’s close-range effort and pushed a Martin Kelly drive on to a post.
Palace, who made nine changes but still fielded a strong team – Wilfried Zaha started – were also dreadfully wasteful, with only eight of their 33 attempts on target.
Too often Zaha tried to beat too many defenders, and substitute Cheikhou Kouyate headed Townsend’s excellent cross against the post on the hour.
But a foul by Rose on Ayew just outside the area was one promising free-kick too many for the visitors to concede, with Schlupp standing up a fine delivery for Ayew to power past McKeown.