Ma'a Nonu has bounced back from a tight calf to start at second-five ahead of Jackson Willison.
"He's been fantastic for us so far, he's had a little bit of a bad run with his first injury and getting straight back into it he just tightened up a bit last week,'' Kirwan said of Nonu.
"He's brought a lot of edge to us and I thought he played really well against the Highlanders and I'm really looking forward to him getting us over the advantage line and doing what Ma'a does best on Friday night.''
Wing Frank Halai has also been reinstated to the starting XV ahead of George Moala.
Weepu has been named on the bench alongside Ihaia West who is poised to make his Super Rugby debut after joining the franchise as a replacement player for the injured Baden Kerr just two weeks ago.
"Bryn has been playing really well so it will be great to have Piri's experience on the bench and with Simon outside him and Ihaia who are both very young men, Piri's experience will be really important so it's great he's been cleared to play,'' Kirwan said.
On the importance of Friday's match against the Waratahs, Kirwan said: "I don't need to hide the fact how important this match is for the franchise, for the team and for our fans. We said last week that against the Hurricanes if we lost away from home then we were going to be under pressure and we're under pressure - we've just got to get out there and go hard. It's going to be a really physical game, I don't know how many Wallabies they've got, I stopped counting, so it's going to be a great match up.''
Friday's curtain-raiser will celebrate 100 years of club rugby at Eden Park and two of the city's oldest clubs will take the field to commemorate the occasion.
Ponsonby, celebrating its 140th anniversary this year, will play North Shore, which was founded in 1873 and is the oldest club in North Harbour. The match kicks off at 3pm.
The Blues team to face the Waratahs at Eden Park on Friday (kick-off 5.35pm) is: Charles Piutau, Frank Halai, Francis Saili, Ma'a Nonu, Lolagi Visinia, Simon Hickey, Bryn Hall, Peter Saili, Luke Braid, Jerome Kaino, Tom Donnelly, Patrick Tuipulotu, Charlie Faumuina, Keven Mealamu, Tony Woodcock. Reserves: James Parsons, Sam Prattley, Angus Ta'avao, Hayden Triggs, Piri Weepu, Steven Luatua, Ihaia West, Pita Ahki.