George and Peter Horne will link up at half-back in a starting XV containing 10 alterations from the side that faced Edinburgh at BT Murrayfield.
A try-scoring cameo on his 50th appearance for the club sees George Horne start at scrum-half, as elder brother Peter starts outside him in the number 10 jersey.
Player/coach Petrus du Plessis is in line to make his first appearance of the 2019/20 season after being named amongst the replacements, joining Oli Kebble and Grant Stewart as the front-row cover on the bench.
Speaking following his selection, Rennie said: "We've got a number of international boys who have played a lot for us over the last few weeks, so we need to rest a few of those guys ahead of Europe. It's a great opportunity for a few guys to make a statement.
"Tom (Gordon) is a really good athlete and explosive with ball in hand, and he's been good for us on both sides of the ball. We're excited to see how he goes. Bruce (Flockhart) has had a few niggles, but he's been very good the times he's got onto the pitch this year and we're looking forward to seeing him go tomorrow.
"We've played some good rugby over the past few weeks and defended well, but it's all about consistency for us. That's going to be key - if we can hang on to the ball we can put Benetton under pressure."
Not available due to injury: Siua Halanukonuka (calf), Sean Kennedy (shoulder), Kiran McDonald (hip), Robbie Nairn (knee), D'arcy Rae (hand), Brandon Thomson (calf), Tommy Seymour (head) and DTH van der Merwe (knee and wrist)