Jordan Cook scored the winner as League Two Grimsby knocked Doncaster out of the Carabao Cup.
The forward, making his first appearance of the season, slotted home the winner after 39 minutes of the first round tie at Blundell Park.
Following their respective league games at the weekend, changes were the order of the day for both sides – seven for Grimsby and six for Doncaster.
Once the action begun, Ben Whiteman fired a couple of long-range attempts wide in anger for the visitors, while Brad Halliday passed up a more clear-cut chance.
Advancing from full-back, the summer signing set his sights from inside the area, but ultimately fired wide under pressure from Liam Gibson.
Despite those warning signs, however, it was Grimsby who edged themselves in front when Cook slotted home from inside the Doncaster area – after linking up superbly with Moses Ogbu.
The visitors went close from a corner after the restart, but substitute Ben Sheaf was unable to direct his effort on target.
Cook went close from range at the other end but genuine opportunities were at a premium for the remainder of the half as Grimsby battled hard to secure their passage through to the second round.