Grimsby Town produced an excellent performance to beat League One Doncaster Rovers and go through to the second round of the Carabao Cup.
After withstanding pressure for long periods of the first half, the Mariners took the lead against the run of play through Jordan Cook.
And they defended well after half-time to keep their visitors at bay and claim a deserved place in the next round, where they will face Macclesfield Town.
Town boss Michael Jolley made seven alterations to the starting XI after Saturday's draw with Bradford City, with only James McKeown, Luke Hendrie, Harry Davis and Elliott Hewitt remaining in the line-up as others were given their opportunity to impress.
McKeown started in goal, with Hendrie, Davis, Mattie Pollock and Liam Gibson forming the defence.
Max Wright, Elliott Hewitt, Cook and Sebastian Ring were the midfielders, with Charles Vernam alongside Moses Ogbu in attack.
Youngsters Brandon McPherson, Joe Hope and Cameron Painter were all handed places on the bench, where they were joined by Matt Green, Jake Hessenthaler, Harry Cardwell and Sam Russell.
Doncaster made the short trip to Cleethorpes for the second time in less than a month, having visited for a pre-season friendly which the Mariners also won 1-0.
The away side made a bright start to this cup tie, with Kieron Sadlier breaking dangerously but sending over a low cross which was stopped by McKeown.
Alex Kiwomya got on the end of a ball over the top of the Town defence four minutes later but as McKeown advanced off his line, the striker could only lift his shot high over the bar.
Whiteman fired off-target from 20 yards as the early Doncaster pressure continued and the midfielder let fly again from a similar distance on 15 minutes but with the same outcome as the ball flew wide.
Ring won a corner on the Grimsby left two minutes later but his delivery was cleared as far as Davis, whose ball back into the box proved too high for Ogbu.
A right-wing cross by Hendrie was caught by visiting keeper Seny Dieng, before a 25-yard effort from Sadlier at the other end was pushed away for a corner by McKeown. Ali Crawford's flag-kick was put wide at the far post by defender Cameron John.
Crawford fired wide of the near post as Doncaster created another chance on 20 minutes, before a low cross by Wright after a run down the right was cleared.
A foul by Cook on Reece James gave the away side a free kick on the left and Crawford tried to catch McKeown out at his near post but the ball deflected off Pollock for a corner, which was clared.
Striker Niall Ennis fired a low shot wide as the visitors continued to look dangerous in attack, before a Ring free kick for Town from near the halfway line was comfortably caught by Dieng.
A shot by Sadlier went across goal and wide of the far post, before a Vernam cross at the other end was headed clear.
Doncaster had created all of the chances but when the deadlock was finally broken on 40 minutes, it was the Mariners who took the lead with their first shot of the game. COOK broke through the middle and after linking up with Ogbu, he got the ball back and found the bottom corner of the net from 12 yards.
The away side immediately went in search of an equaliser and they almost had it when a low cross found Sadlier but his first-time shot from close range was pushed over the bar by McKeown.
The Mariners went close to doubling their advantage when Vernam let fly from the edge of the penalty area but keeper Dieng was equal to it, diving to tip the ball over his bar for a corner.
Two added minutes were played at the end of the half and another shot by Vernam was deflected and collected by Dieng at the second attempt.
That proved to be the last chance of the half, with Grimsby holding their lead at the interval.
Ben Sheaf replaced Whiteman in the Doncaster midfield before the restart and Town started brightly, with Ogbu and Vrnam linking up well in the early stages.
At the other end, Ring did well to stop Sadlier at the expense of a corner, which did not lead to a goalscoring opportuniy.
Wright did well to get the ball away for another corner soon afterwards and this time, Sadlier's header flew across goal and wide of the far post.
Ennis shot wide and Sadlier sent an effort over the bar as the away strikers coninued to missfire.
A Doncaster corner was cleared after McKeown had been first to the ball from the flag, before Jon Taylor was sent on in place of Kiwomya in the visitors' second change.
Another away corner came on the right on 64 minutes but Crawford's delivery went straight iinto McKeown's hands.
Hessenthaler was sent on in place of Gibson just after Ogbu was fouled to give Town a free kick. The substitute took it himself but Ring's shot was blocked after the ball was only half-cleared.
Taylor was ruled to be offside at the other end after another shot by Sadlier was saved.
An obstruction by Taylor on Cook gave the hosts another free kick inside the Doncaster half and after it was not fully dealt with, Ogbu did well to win a corner but Hessenthaler's ball from the flag was cleared.
A foul on Ogbu brought a free kick on the Grimsby right on 75 minutes but Hessenthaler's ball was headed wide by Davis at the far post.
Taylor was shown the first yellow card of the evening after a number of infringements, before Green replaced Ring for Town and Alfie May came on for Matty Blair in the red and white of Doncaster.
Crawford fired over the bar on 81 minutes after a cross was cleared, then a ball from Wright went across goal and out of play after a Hessenthaler free kick at the other end.
Green was fouled after showing persistence near the corner flag but Town could not profit from the resulting free kick.
Doncaster pushed forward in the closing stages of the game in search of an equaliser and Town were forced to endure an additional four minutes at the end of the game.
But that elusive Doncaster goal was not to come and the Mariners were finally able to celebrate a place in the second round of the competition.
They will face Macclesfield Town for the right to go through to round three but attention first turns back to the league and a trip to Forest Green Rovers on Saturday.
Town: McKeown, Hendrie, Pollock, Davis, Gibson, Hewitt, Ring, Cook, Wright, Vernam, Ogbu
Subs: Russell, Hope, Hessenthaler, McPherson, Painter, Green, Cardwell.
Rovers: Seny Timothy Dieng, Brad Halliday, Reece James , Tom Anderson, Cameron John, Benjamin Whiteman (C), Alex Kiwomya, Matty Blair, Ali Crawford, Kieran Sadlier, Niall Ennis.
Subs: Ian Lawlor, Shane Blaney, Madger Gomes, Ben Sheaf, Jon Taylor, Will Longbottom, Alfie May.
Referee: John Brooks
Attendance: 2470 (478)
Next Up: Forest Green Rovers (A)