Paul Gallen preserved his perfect boxing record a fourth-round TKO win over Herman Ene-Purcell in front of a full house at Rumours International in Toowoomba on Friday.

Gallen controlled the bout from the opening bell and scored a controversial knockdown in the second round, and completed the win two minutes in to the penultimate round after unleashing a number of big shots on Ene-Purcell that led to his corner throwing in the towel.

"It was great to get the win tonight, and credit to Herman Ene-Purcell," Gallen said. "He certainly proved how tough he is."

Gallen is now unbeaten in five pro fights (3 KO wins). Ene-Purcell falls to 7-5 (4 KOs).

The last time they fought, in February of 2014 when Gallen made his pro debut, he stopped Ene-Purcell in two rounds.

The Blues' and Sharks' NRL leader is eager to a showdown with Sonny Bill Williams (7-0, 3 KOs).

Gallen, along with SBW and Anthony Mundine, has become one of the highest profile of the many footballers to enter a boxing ring and has thrown away his pugilistic P plates.

"I tell him I don't think of him now as a league player who does a bit of boxing. I look at him as a boxer," said Graham Shaw, who also trains multi-middleweight world-title winner Daniel Geale.