Dan Parks has been named in the number 10 jersey. The veteran out-half is 27 points shy of reaching the milestone of 500 Heineken Cup points. Mayo-born Gavin Duffy also returns to the back-line this week, starting at fullback.
The second row partnership of Connacht's most-capped player Michael Swift and captain Craig Clarke returns to boost the pack.
There is a reshuffle in the back row with John Muldoon moving to number 8 in place of the injured Eoin McKeon. Andrew Browne slots in to blindside flanker while Jake Heenan remains on the openside.
Galway-born back Tiernan O'Halloran is named on the replacements bench.
Speaking about the province's final game of the pool stages, Lam said: "This is a huge game for Connacht Rugby, we all know that. Win and we qualify for a quarter-final in Europe.
"Big games require your big players to step up and lead the way, so it's great to be able to call on four of our most experienced players - Gavin, Dan, Swifty and Craig - this week.
"We were unfortunate to lose Eoin McKeon to injury in training this week. He has had to have surgery on his hand and is likely to be out of action for up to two months. It's a big loss to our back row resources.
"We have a lot of respect for what Saracens are achieving. They are well-coached, well-resourced and top of the English Premiership, with an excellent stadium.
"They have only lost once on this new 4G surface and have racked up a high number of points against opposition teams. If we play as individuals, it will be a long day at the office tomorrow. It's all about our team effort."
CONNACHT (v Saracens): Gavin Duffy; Fionn Carr, Robbie Henshaw, Eoin Griffin, Matt Healy; Dan Parks, Kieran Marmion; Brett Wilkinson, Sean Henry, Nathan White, Michael Swift, Craig Clarke (capt), Andrew Browne, Jake Heenan, John Muldoon.
Replacements: Jason Harris-Wright, Denis Buckley, Rodney Ah You, Michael Kearney, George Naoupu, Paul O'Donohoe, Darragh Leader, Tiernan O'Halloran.