Sharks sweat over Lambie injury
Lambie, who has suffered a succession of injuries in the last few seasons, hurt his back in a tackle in the 37-14 win over the Waratahs at the weekend.
"At this stage, I am not too sure [about the extent of the injury]," Du Preez said.
"It is obviously not great. He is a tough guy, but hopefully, it's not too serious."
Loose forward Philip van der Walt went to the hospital for scans after an on-field collision.
However, he will go through all the concussion protocols before a call on his availability is made.
French import Clement Poitrenaud is struggling with a groin strain, but the coach felt he should be fine to face the Southern Kings in Durban this coming Saturday.
Du Preez said there was a "really good vibe" in the camp after back-to-back victories.
"The players have worked really hard," the coach said, adding: "We were very disappointed with that first game against the Reds.
"However, there has been good improvement every game."
