Coleraine beat Bertie Peacock Youths 1-0 in a tight derby clash in Tuesday's Minor section at the SuperCupNI .
A second half goal from Tommy Rogers sealed the crucial victory for John Gregg's side at the Showgrounds.
Rogers coolly slotted home after being played through eight minutes after the break.
Coleraine's win leaves everything to play for in Group C after Glentoran beat Global Premier Soccer 3-1.
Jude Johnson scored twice for the Glens with Calum Hamilton also on target.
All four teams are now on three points going into Wednesday's final group games.
In Group D, holders Greenisland fought out a thrilling 3-3 draw with Ballymena United in Ahoghill.
Joel O'Rourke scored twice while Theo McToal got the third for Greenisland.
Ballymena's scorers were Robbie Spiers, Kai McCormick and Calum Douglas.
Larne bounced back from Monday's defeat to the Sky Blues with a spirited 4-2 win over Glenavon.
Jack hastings scored twice for the Co Antrim boys, with Aodhan Doherty and Kristian McVeigh also on target. Jesse Turner and Matty Hughes replied for the Lurgan Blues.
Finn Harps were convincing 4-0 winners over Linfield in Group A - Tiernan McGinty, Aaron McLaughlin, Shaunie Bradley and Shaun Patton on target.
Elsewhere, Ballyclare Colts saw off Portadown 3-1 with Logan McWilliams, Ross Smyth and Zak McGall scoring for the winners.
In Group B, Dungannon Utd continued their impressive SuperCupNI campaign with a 3-0 win over Chinese visitors Beijing BFA.
Goals from Sam Anderson (2) and Aidan Hegarty sealed the success.
Ballinamallard Utd impressed in a 4-1 victory over Warrenpoint, with James Taylor, Luke McAnespy and Ethan Abercrombie (2) getting the goals.
Group A
Ballyclare Colts 3-1 Portadown
Linfield 0-4 Finn Harps
Group B
Dungannon United 3-0 Beijing BFA
Ballinamallard United 4-1 Warrenpoint
Group C
Glentoran 3-1 Global Premier Soccer
Coleraine FC 1-0 Bertie Peacock Youths
Group D
Glenavon 2-4 Larne FC
Greenisland 3-3 Ballymena United
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