Chris Vermeulen says he may sit out the two World Superbike races at Donington Park this weekend as a precaution, but will almost certainly participate in the preceding practice and qualifying sessions.

The Australian, who has battled a serious knee injury for more than a year now, returns to competitive action for the first time in eight months at Donington Park having been given the green light by doctors to compete aboard the Kawasaki.

However, while Vermeulen, who tested the ZX-10R briefly during a private session at Cadwell Park this week, is excited to be rejoining the WSBK fray, he may stop short of actually racing this weekend.

"I will ride to use this weekend but almost as a test at first," he said. "From my doctor's point of view I am improving well, but I should just be increasing my riding step-by-step. I rode at Cadwell Park, did about 30 laps in total on the Ninja ZX-10R, and it felt really good.

"My speed was OK but I was not going to break any lap records. My knee started to swell up afterwards so we rested it up. We have decided to ride this weekend but to look at it as a test; not only for my knee but to get some information on the bike, to ride the new generation Pirellis and just get out there on track and see how it goes.

"If it goes well we will race, but at this stage races may be quite difficult."

Moving forward, Vermeulen will compete in all sessions at Assen, whie it is anticipated that he will be back to full speed by Monza.