Geelong speedster Steve Motlop has decided to join Port Adelaide, with the Power confirming the news on Friday afternoon.

Motlop will join the Power on a four-year deal if Geelong opt not to match Port's free agency bid, which the Cats have three days to make a decision on.

The Cats will most receive a second round pick as compensation for losing the 26-year-old.

The Power beat cross-town rivals, Adelaide and the Gold Coast Suns to secure Motlop's services.

Motlop played 23 games for the Cats this season, averaging 19.3 disposals and kicking 22 goals.

He played a total of 135 games and kicked 175 goals for Geelong since being selected with pick No.39 draft pick.