It could be the first appearance for Pienaar for a South African club side in nine years.
Between 2004 and 2010 he represented the Sharks in 32 Currie Cup games and 67 Super Rugby matches. He moved to Ulster where he played for seven seasons. The IRFU refused to renew his contract at the Belfast based club at which point he moved to France with his family to take up a lucrative deal with Montpellier.
In the backline, Tapiwa Mafura will be starting on the wing and making his Currie Cup debut, replacing the injured William Small-Smith.
Van der Merwe will wear the No.6 jersey with Junior Pokomela moving to the No.7 flank.
The Golden Lions are also unbeaten with nine points from their two matches.
Free State Cheetahs: 15 Darron Adonis, 14 Tapiwa Mafura, 13 Benhard Janse van Rensburg, 12 Dries Swanepoel, 11 Sibahle Maxwane, 10 Tian Schoeman, 9 Tian Meyer, (captain), 8 Henco Venter, 7 Junior Pokomela, 6 Marnus van der Merwe, 5 Walt Steenkamp, 4 Sitno Manjesi, 3 Aranos Coetzee, 2 Joseph Dweba, 1 Retshegofaditswe Nche.
Replacements: 16 Jacques du Toit, 17 Charles Marais, 18 Reinach Venter, 19 Jean-Pierre du Preez, 20 Abongile Nonkontwana, 21 Gerhard Olivier, 22 Ruan Pienaar, 23 Louis Fouche.
Date: Friday, August 2
Venue: Free State Stadium, Bloemfontein
Kick-off: 19.15 (17.15 GMT)
Referee: Jaco Peyper
Assistant referees: Marius van der Westhuizen, Griffin Colby
TMO: Lourens van der Merwe
Sign up to our mailing list here and we’ll keep you up to the minute with weekly updates from the world of rugby.