Otis Khan scored twice to earn Grimsby Town a place in the third round of the FA Cup as they beat Cambridge United at the Abbey Stadium.

After an even first half, the Mariners looked the more dangerous after the break and got their reward when Khan put them ahead on the hour. Cambridge came into the game on a long run of games without a goal and they looked short of attacking threat but found themselves level nine minutes from time when substitute Sam Smith headed home the equaliser. But Town were not to be denied and Khan’s 90th minute winner sent the 726 travelling supporters wild as they celebrated a second consecutive FA Cup victory over League One opposition.

Two changes were made to the Grimsby starting XI from the league draw with Stevenage last week, with Gavan Holohan and Brendan Kiernan coming in for Andy Smith and Bryn Morris. Goalkeeper Max Crocombe lined up behind a back four of Michee Efete, Luke Waterfall, Niall Maher and Danny Amos, while Kieran Green sat behind a midfield of Kiernan, Holohan, Harry Clifton and Khan as John McAtee led the attack. Nine substitutes can be named for FA Cup ties, so Jamie Pardington, Alex Hunt, Shaun Pearson, Evan Khouri, Danilo Orsi, Lewis Richardson and Keyendrah Simmonds all joined Smith and Morris on the bench.

While the Mariners powered into the second round with a 5-1 demolition of Plymouth Argyle, Cambridge had to come through a penalty shootout to get to this stage of the competition after two goalless draws with National League North Curzon Ashton. Mark Bonner’s side were aiming to stop a five-game run without scoring in all competitions and would look to the likes of striker Joe Ironside to hit the net.

A cross from Kiernan on the right drifted wide of the far post for a goal kick as Town attacked for the first time on three minutes, before McAtee missed the target with a speculative shot from distance.

Ironside was caught offside as Cambridge made their first move into the Grimsby penalty area, then a 20-yard strike from Clifton was stopped by home keeper Will Mannion.

McAtee charged down an attempted clearance by Mannion soon afterwards but the ball spun away from goal, before Holohan and Efete combined to block a cross from Harrison Dunk at the other end.

A foul by Efete on Dunk gave the hosts a free kick in a dangerous position on their left on 11 minutes but the right-back was in place at the far post to head Lewis Simper’s delivery clear.

Cambridge won the game’s first corner on the quarter-hour and the low ball from it was cleared at the near post as far as James Brophy, who fired well over the bar from 25 yards.

Kiernan had the best chance so far two minutes later after good play by the Mariners around the edge of the box. The ball eventually fell for the winger but he could not keep his shot down.

Neither goalkeeper had been called into serious action as the midway point of the half passed, with Cambridge seeing more of the ball but Town looking comfortable in defence.

A cross from Amos on the left was caught by Mannion after a good spell of away possession, before Green was shown the first yellow card of the game for stopping Shilow Tracey from taking a quick free kick. The ball from it was headed away by Waterfall and a follow-up cross from Brophy was caught by Crocombe.

Kiernan did well to hold off his man and work his way into the box on the half-hour but could not find a team-mate with a cross to the far post, then Waterfall had to put in a good block at the other end to deny Harvey Knibbs. The resulting corner was headed against his own bar by Green, before the ball was eventually scrambled clear.

A Holohan cross from the right was headed away at the far post and soon afterwards, Kiernan sent a drive just over the bar from 20 yards as Town looked for the opening goal.

Efete went down under a challenge inside the box on 38 minutes but play continued and a close-range effort from Clifton was blocked for a corner on the right. Amos’ delivery from the flag was headed out for a Town throw-in on the left.

Another corner came soon afterwards as the Grimsby pressure continued but after the ball from it was played short, Khan’s cross was scrambled clear.

Cambridge captain Paul Digby was booked four minutes before the break after bringing Khan down inside the Town half and although the free kick came to nothing, McAtee had a shooting opportunity moments later but his strike was straight at Mannion.

Kiernan sent a shot just wide from outside the box as he appeared to be pulled back and another corner came as the half moved into one added minute, with the visitors still on the front foot. Amos’ delivery was pushed out to Kiernan, whose shot was blocked.

Waterfall became the latest to see the referee’s yellow card in the closing seconds of a half where both sides had played some good football, although neither had been able to force a breakthrough.

No changes were made before the restart and after a bright opening to the second half by Town, it was the hosts who won the first corner but the ball from the flag was dealt with by Green.

Knibbs lifted a shot over the bar from the edge of the box after Brophy did well to get past Efete down the home left, then a deflected McAtee shot at the other end was tipped over the bar by Mannion for a Grimsby corner. Amos’ ball from the flag was headed wide for a goal kick.

A chipped cross from Khan was caught by Mannion after good work by Holohan to win the ball and find the winger.

Cambridge then had a spell of possession without troubling Crocombe or his defence, before a ball from Clifton was just too far ahead of McAtee and a cross from Efete was caught.

Town had looked the more dangerous in the second half though and on the hour mark, they took the lead. A great cross-field ball found Kiernan on the right and he sent it into the box, where an initial shot from Holohan was parried by Mannion and KHAN slammed the rebound into the net.

Cambridge’s response saw Tracey chip a cross from the right which was comfortable for Crocombe and the hosts then made a double substitution, with Sam Smith and Jack Lankester replacing Dunk and Tracey.

A cross from the home left was deflected behind for a corner on 70 minutes but it was headed clear.

Town had an opportunity to put the result beyond doubt when Kiernan threaded a ball through for McAtee but after running onto it, he was unable to beat Mannion, who raced off his line to make a good block.

A long-range shot by Holohan was deflected wide by Kiernan at the end of another good attacking move by the Mariners, who were now firmly on top and looking to add to their lead.

Jubril Okedina could only find the grateful arms of Crocombe with a cross from the right as the hosts struggled to create danger.

Another double substitution saw Saikou Janneh and Ben Worman replace Knibbs and Simper on 76 minutes, with Cambridge searching for a route back into the contest.

And that way back into the game came for them with nine minutes to go, as SMITH got to a cross first and his header back across goal went past Crocombe and crept into the far corner of the net to make it 1-1.

McAtee was booked for a foul on George Williams as the momentum had suddenly shifted, with the previously quietened home crowd now right behind their team as they looked to complete the comeback.

Kiernan lifted a shot over the bar at the end of a Mariners counter-attack on 84 minutes, then another attack broke down when a pass from Clifton towards Kiernan was intercepted.

The Mariners should have been ahead again with two minutes remaining, as Amos did superbly well to nutmeg his man and get vto the by-line before pulling the ball back across goal. Mannion got to it but pushed the ball out to Holohan, although the midfielder was unable to find the net from eight yards and could only watch his shot go over the bar.

Simmonds replaced McAtee in the Town attack and the substitute was the creator as the visitors snatched the advantage back just before the game moved into four minutes of added time. His touch sent KHAN clear through the middle and the winger kept his composure to slot past Mannion for his second of the game in front of the travelling fans.

Smith came on after the goal and there was still some defending to do before the Mariners could be sure of their place in the hat for round three, with a low drive from Digby blocked at the edge of the box.

Khouri and Morris also came on for the closing stages of the game as Town closed out an excellent victory.

They will now look forward to Monday evening’s third round draw and a possible meeting with a Premier League or Championship club, before the focus switches back to the league programme for Saturday’s trip to AFC Wimbledon.