The 20-year-old Cardiff Blues wing made his British & Irish Lions debut against the Free State Cheetahs in Bloemfontein last weekend after spending 10 days at home overcoming his thigh problems.
But he aggravated the injury at the end of the training session yesterdat and has been withdrawn from the Lions replacements bench as a precaution.
“He was examined by the medical team this morning and was comfortable. However, in order to enable an accurate diagnosis he is currently having a scan,” said a Lions spokesman.
“As a preliminary measure he will be unavailable for Wednesday’s game and James Hook will take his place on the bench.”
Meanwhile, the youngest Lions tourist has spoken about his added responsibilities of taking care of the team mascot, Lennie the Lion.
“I can understand now why Keith Earls was pleased to hand him over because he is hard work. He keeps going missing all the time and can’t keep still.
“But I have to say it is an honour to be looking after him. It is a tradition of the Lions and I am pleased to be involved with that.”