Matt Fagerson will make his 50th Glasgow Warriors appearance in a team showing three changes from last weekend's defeat in Bloemfontein.
Rennie has elected to make two alterations to the back-line that kicked off against the Toyota Cheetahs, with Ruaridh Jackson promoted to the starting XV after coming off the bench in South Africa.
The club centurion is joined by Rory Hughes and Kyle Steyn in the back-three, the wing duo having been selected to start for a second successive week.
Stafford McDowall also comes into the back division, partnering Huw Jones in midfield to make his first start of the campaign, whilst an unchanged half-back combination sees Nick Frisby and Brandon Thomson continue at nine and ten respectively.
The final change to the starting XV comes in the pack, as Kiran McDonald comes into the second-row to partner Tim Swinson.
An unchanged front-row sees Oli Kebble and D'arcy Rae continue either side of Grant Stewart, whilst Rob Harley and captain Callum Gibbins flank Matt Fagerson in the back-row.
After both making their competitive debuts for the Warriors in South Africa last weekend, Johnny Matthews and Jamie Dobie are in line to make a first competitive appearance at Scotstoun from the replacements' bench.
Tom Gordon also comes into the squad to take the 19 jersey, whilst Glenn Bryce and Patrick Kelly join the replacements for the club's first home outing of the new season.
The remainder of the matchday 23 is unchanged, with Alex Allan, Adam Nicol and Chris Fusaro all having come off the bench in South Africa.
Head Coach Rennie paid tribute to Fagerson ahead of his landmark appearance, as well as highlighting the reaction he expects from his side tomorrow night.
"The most impressive thing for me is the number of games that Matt has started in his 50 caps," said Rennie.
"It's a phenomenal achievement for him to reach 50 caps at the age of 21, but to have 40 of those as starts is incredible. He's a player we rate really highly and those figures highlight the respect we have for him.
"He offers a real point of difference with his explosive ball-carrying. It'll be a proud day for him and his family.
"The reaction (this week) has been exactly what we expect from the players. It was a disappointing defeat to a Cheetahs side that played very well, but we were miles off it.
"We had a pretty brutal review and then the players have responded well in training. We're expecting another tough test this weekend, though, against a very good Scarlets side."
14 Kyle Steyn
13 Huw Jones
12 Stafford McDowall
11 Rory Hughes
10 Brandon Thomson
9 Nick Frisby
1 Oli Kebble
2 Grant Stewart
3 D'arcy Rae
4 Kiran McDonald
5 Tim Swinson
6 Robert Harley
7 Callum Gibbins (Captain)
8 Matt Fagerson
Substitutes
16 Johnny Matthews
17 Alex Allan
18 Adam Nicol
19 Tom Gordon
20 Chris Fusaro
21 Jamie Dobie
22 Patrick Kelly
23 Glenn Bryce
Not available due to injury: Andrew Davidson (head), Bruce Flockhart (shoulder), Nick Grigg (knee), Lee Jones (hamstring), Ali Price (foot) and Jale Vakaloloma (shoulder)