Watch: Early whistle costs Preds opening goal after ref loses sight of puck

It's referee Kevin Pollock's worst nightmare.

Early in the second period of a scoreless Game 6 of the Stanley Cup Final on Sunday, Pollock lost sight of the puck after Nashville Predators forward Filip Forsberg fired it on Matt Murray - who didn't have control of it - and blew the play dead a second before Colton Sissons put it into the open net.

The play was not reviewable, and the call on the ice stood despite the fact the four officials on the ice got together to discuss the play, on which it was clear Murray didn't have possession.

The Predators and their fans were unsurprisingly not happy with the ruling, which ended up proving as costly as costly gets.

Penguins forward - and former Predator - Patric Hornqvist scored the Stanley Cup-winning goal at 18:25 of the third period, breaking a 0-0 tie by banking in a puck off Pekka Rinne from behind the net.

The Penguins won the game 2-0, after an empty-net goal, giving Pittsburgh its fifth Stanley Cup in club history.