Fifita showed his impact potential at the highest level, with three shock-and-awe stints giving him some staggering performance numbers from his most impressive performance in his short 16 game NRL career.

However, when he spoke to The Area News yesterday, Sheens said while Fifita's performance last round was good for his self-belief heading into the finals, his explosive 41 minutes would be soon forgotten if he failed to back it up next week.

"He did his job, we don't want to get too carried away with him just yet, but he showed what we all know that he's got plenty of potential," Sheens said.

"The weekend was one good effort and we'd like to see a few more, but it's the right end of the season for us and it gives him confidence which is good for him.

"With the big games coming up and delivering at semi-finals, that's where you talk about being a professional player.

"There's a long way to go, but it's a step in the right direction for the young bloke."

The Waratahs junior equalled the NRL record this season for line breaks, with the 114kg prop breathing fresh air four times on his way to bagging the first double in is NRL career.

Fifita was a star of the Tigers' Toyota Cup side that was pipped on the bell in the 2009 grand final by the Melbourne Storm, but the Kangaroos coach said he still undergoing his NRL defensively.

"He's blessed with a bit of leg speed but defensively he gets caught out at times with some poor decision making and a bit of grabbing," Sheens said.

"That happens in most kids his age, whether it's (Jersey) Flegg which was under 20s or at a junior level you're only talking about 18 to 19-year-old kids and it's (Toyota Cup) been a great innovation of the game.

"At the moment I see him like all young players that come up (to the NRL), and it's not tackling it's about making decisions which is the issue and the hard work and the back-to-back efforts you need to make, and that all takes time to develop that fitness and mental toughness.