Pretorius is one of three changes to the side that narrowly lost out to Glasgow Warriors in the opening round of action last week.
The talismanic Wales international forward, who made his international debut during the summer tour to Japan, is named in the back row alongside Josh Navidi and Robin Copeland.
British & Irish Lions star Alex Cuthbert will make his first appearance of the season while Dafydd Hewitt is called up to play at inside centre.
Lou Reed and Kristian Dacey are both named among the replacements and could make their first appearances of the league season.
Director of Rugby Phil Davies admitted his side were fired-up for the first league game at the Arms Park this season against a talented Connacht outfit.
"We are coming up against a very good team in Connacht and they have brought in some very talented players during the summer," he said. "Craig Clarke, the former Waikato Chiefs captain, is a fantastic player and someone we've been aware of. He will galvanise the team.
"Pat Lam has taken over the coaching so I think there will be a slightly different emphasis in terms of the style of rugby they adopt. It will be a big challenge and we've got to perform well.
He added: "Our ambition this season will be to put on a spectacle every time we play at the Arms Park and use the new surface to our advantage.
"We are trying to play an expansive style of rugby, but we also know we need to be effective with all facets of our game.
"What we must do is develop an all-round game that suits each and every occasion that we face. No matter what surface you play on, it's about having that balance in your game and being to execute it."
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Cardiff Blues: 15 Tom Williams, 14 Alex Cuthbert, 13 Owen Williams, 12 Dafydd Hewitt, 11 Harry Robinson, 10 Rhys Patchell, 9 Lloyd Williams;
1 Taufa'ao Filise, 2 Matthew Rees (c), 3 Scott Andrews, 4 Bradley Davies, 5 Filo Paulo, 6 Andries Pretorius, 7 Josh Navidi, 8 Robin Copeland.
Replacements: 16 Kristian Dacey, 17 Sam Hobbs, 18 Benoit Bourrust, 19 Lou Reed, 20 Macauley Cook, 21 Lewis Jones, 22 Gareth Davies, 23 Gavin Evans.