NSW Waratahs captain Dave Dennis has one final mental hurdle to clear on Friday, his comeback from a third knee reconstruction.

Wallabies blindside flanker Dennis missed the latter stages of the Waratahs 2014 Super Rugby title-winning campaign.

Seven months on, he will spring back into action in their final trial against the Chiefs at Campbelltown, where he expects to play the last 30 to 40 minutes.

“It’s been a tough six or seven months, but I’ve done it before,” Dennis said.

“I don’t know whether that’s a good or bad thing, but I’ve known what’s required and the body feels good.

“I’ve just got to get over that last mental hurdle of getting out there and playing and tackling a few guys and running at a few guys.”

Dennis confirmed he will spend time in the second row this year, as the Tahs look to replace valued workhorse Kane Douglas, who left to play in Ireland.

Dennis played a few games as a lock in the early stages of his rep career.

“The style of rugby we play, there’s not too much difference between that and six, aside from the scrummaging,” Dennis said.

Asked if he felt playing lock would enhance his national selection prospects, Dennis said: “What will enhance my selection is playing well, regardless of what number I’ve got.”

Waratahs coach Michael Cheika is expected to give virtually all of his Wallabies, bar injured winger Peter Betham, a run against the Chiefs.

Most of the pre-match focus has been on Waratahs fullback Israel Folau and Chiefs centre Sonny Bill Williams playing against each other for the first time since 2007, when they were on different NRL teams

“That seems to be all the talk and fair enough, they are two world class players,” Dennis said.