BRISBANE Lions midfielder Rhys Mathieson will miss up to six weeks after injuring his ankle at training.

It continues a tough run of training mishaps for the Lions, with Mathieson joining Josh Schache (knee) and Jono Freeman (cheekbone) as recent casualties away from games.

Lions head of medical Peter Blanch told the club's website that Mathieson has a bad sprain.

"The sprain resulted in some ligament issues, including ligaments in the top of his ankle," Blanch said.

"Luckily it wasn’t bad enough that it required surgery, but he will be in rehabilitation for the next four to six weeks."

Mathieson is on the fringe of the club's best 22 but was unlikely to be in consideration for Saturday night's round one against Gold Coast after not playing in the final pre-season match.

Mathieson is currently in a moon boot.