FIFA investigating Tim Cahill celebration

World football governing body FIFA has launched an investigation amid suggestions that Tim Cahill was paid for a sponsored celebration during Australia's win over Syria.

The Melbourne City midfielder scored twice in the World Cup qualification playoff tie on Tuesday morning, including a goal in extra time to earn the Aussies a 3-2 aggregate victory.

Cahill celebrated his winner by making a 'T' sign with his hands, which Australian online travel agency TripADeal later thanked him for on social media.

"Did you catch @tim_cahill, our new brand ambassador, doing . . .