Chris Vermeulen's stuttering return to World Superbike competition at Monza received another setback as he was forced to sit out Monza because of an elbow injury.

The Australian, who has been battling issues with his knee for more than a year now and has started just one race this season, fell heavily during Friday free practice, hurting his elbow when it was caught under his Kawasaki.

Forced to sit out Saturday, though Vermeulen was hoping to return for the races, doctors' advice would force him to withdraw altogether.

"My elbow is the only problem, even though the rest of me is a bit sore after my Friday fall. They say the gash in my elbow needs about six stitches in it and the elbow has swollen up a lot inside. I have been having it drained of fluid a couple of times a day.

"They say there is nothing majorly wrong with my elbow and it was only a problem because it got stuck under the bike when I crashed. I [was] advised not to ride this weekend but the good thing is that my knee feels a lot better and we were reasonably quick after only a few laps."