Pretoria - Bulls coach Nollis Marais has had his suspicions confirmed with the news that second rower Lood de Jager will be unavailable for Saturday's Super Rugby clash against the Cheetahs in Bloemfontein.
De Jager, on his Bulls debut, left the field towards the end of the first half against the Stormers at Newlands on Saturday with what was later confirmed as a concussion.
"He is in a stable condition and will follow World Rugby's 'Return to Play' protocol on the sidelines," a statement from the Bulls read.
The good news for the Pretoria-based franchise is that centre Jan Serfontein and prop Martin Dreyer have both been cleared to play against the Cheetahs this weekend.
Arno Botha, Jannes Kirsten and former Springbok captain Adriaan Strauss have all returned to training this week, but they will remain unavailable for selection this weekend.
The Bulls lost 37-24 against the Stormers and will be desperate for a win over the Cheetahs to get their season going.
Kick-off in that match is at 19:30.