Western Force coach Richard Graham believes he has uncovered a hidden gem in the form of NRL rising star Will Tupou, who will link up with the Perth-based franchise for the next two Super Rugby seasons.

Auckland-born Tupou - a 196cm, 104kg powerhouse - grew up in Queensland and played rugby union throughout his school years before switching to league as an 18-year-old.

The outside back spent two years with the Brisbane Broncos' development squad before moving to the Cowboys, where he has scored seven tries in 21 first-grade appearances.

Graham said he had kept a keen eye on 21-year-old Tupou for almost a year before finally landing his man, who will join Jordan Rapana as recruits to have crossed to the Force from NRL ranks since the end of last season.

"When I took over the job last year, I spoke to a lot of people from schools just to see what they'd had over the years and was there anything out of the blue that I could find," Graham said on Tuesday.

"Will's name came up then but he was contracted (with the Cowboys) until the end of this season.

"So I'd been having discussions but they were loose conversations really until a couple of months ago.

"I think he's a fantastic acquisition for us.

"Willie's grown up with rugby and, in the last four years, has been in a very good league environment.

"(He's a) huge man - six-foot three and 105kg.

"He's very committed to running the lines and will commit defenders. And needless to say, given his size, he's very physical in defence."

Tupou, a member of the 2007 Australian Schoolboys side, said he was keen to give rugby union another crack following his impressive junior stint in the code.

"I enjoyed my time in league and (I'm) happy that I gave it a go but playing rugby at the highest level is what I always wanted to do and it's something that myself and my Dad have talked about since I was a kid," Tupou said.

Tupou's recruitment leaves just two more spots on the Force's 30-man roster to fill, including their marquee position.

"I've got my eye on a couple of marquee players but we'll probably wait until the World Cup and see what comes out of that," Graham said.

"That marquee position at this stage will be an outside back."

Meanwhile, Graham said the Force's upcoming two-game tour of Samoa would reveal a lot about the mental mindset of his group.

"The tour offers us an opportunity to see who's going to grow as leaders and players without our Wallaby contingent," Graham said ahead of games against the Samoan Test team on August 20 and 27.

"We've named Sam (Wykes) as our captain and I think he'll do a wonderful job.

"He's set a very high standard for himself and also the teammates around him."

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