Paul Bird Motorsports' Chris Vermeulen is optimistic that he'll be able to race in the next round of the World Superbike Championship next weekend.Vermeulen suffered a knee injury in his crash in the opening round of the series at Phillip Island in February is hopeful of rejoining teammate Tom Sykes at the Dutch round in Assen, April 24-25."My knee is improving every day since I had keyhole surgery over a week ago and I have a good feeling in most of its range," Vermeulen said in a team release. "The difficult part now is getting enough bend, but also strength and stability in my knee to race at Assen because I don't want to turn up to just ride around. I am getting physiotherapy every day and it's still a week until I need to be on the bike so I am optimistic that in that time it will have improved even more by then. I really enjoy racing at Assen and have had successful results there in both Superbikes and in MotoGP; I also get a lot of support there because of my Dutch heritage. I therefore hope that I can put on a good show and be fit enough to compete and join the team once again."Sykes, meanwhile, has been struggling on the second Kawasaki. The Brit is currently 16th in the championship after scoring just 13 points in six races (three rounds)."Valencia was a tough race for us, but I feel that we can take a lot of positives from those races," the Brit said. "We worked hard all weekend on chassis issues and finally it came together on Sunday morning and we produced some good consistent lap times in the race. Looking ahead to Assen, I hope we can continue with the progress we have made over the past few races and put in solid on-track performances throughout the weekend. The Assen circuit hasn't always been so kind to the ZX-10R, but we're due some good fortune and with Chris coming back, we hope that this race we'll be able to showcase the hard work that both myself and the team are putting in behind the scenes."