A poor second half on Saturday ruined the Gold Coast Football Club's chances of a TAC Cup top-two finish, and was behind a disappointing loss to the Geelong Falcons.

The top of the table showdown between the under-18 clubs at Carrara was doubly important for the GCFC.

A win would have meant second spot and the double chance in the finals (the Falcons were already assured of top spot).

But the Coast's 14-7 (91) to 6-14 (50) loss meant they dropped to fifth as a result of other results and they now meet the Northern Knights in Melbourne on Saturday in a cut-throat elimination final.

With a lot on the line, the GCFC came out hard and looked good early.

The scores were level at quarter-time and the Coast then turned it on in the second term. They had all the ball, the momentum and controlled the quarter.

At half-time they were up by two goals, but it should have been by about seven goals.

They hit the post three times and squandered countless shots on goal.

Geelong appeared to be struggling in the 29C heat and many would have backed the Coast to finish them off. But the Falcons were a different team after the main break and showed why they have lost just one game this season. Alik Magin, Matt Fowler, Jake Crawford, Mitch Harley and Nathan Spring were the GCFC's best.

By Nick Smart, Courtesy of The Gold Coast Bulletin