The Johannesburg Super Rugby franchise beat the Blues 39-36 at Ellis Park and Coetzee was the only injury from the result.
Hooker Coetzee picked up a hairline tear to his right medial cruciate ligament (knee).
“Willie Wepener will move in [to start against the Reds on Saturday],We still have to make a call on who will come onto the [replacement] bench. The guy who will come onto the bench will almost certainly be a youngster, who have not played any Super Rugby.” Said Coach Johann Ackerman.
“It is just a pity, because we have started to get some nice continuity in selection, especially among the forwards, The last few weeks we had the same set of forwards and we lose that.” he added.
“I also feel sorry for Robbie [Coetzee],” he said, adding: “He could be sidelined for up to six weeks, depending on the result of the scan. He has been playing such good rugby the last few weeks.”
The Lions did however get some good news as the Andries Coetzee, Alwyn Hollenbach, Lionel Mapoe and Michael Bondesio have all recovered from their respective injuries and will be ready to return to action this weekend and will be considered for the Lions this weekend.