Rossi's injuries are not as bad as first feared

The Yamaha rider returned in the afternoon to clock the 12th best time after dislocating an ankle bone and fracturing a bone in his right hand.

"I'm OK and I'd like everyone to relax about it, even if it's been quite hard for me to ride," said Rossi.

"I had all the examinations necessary to check if everything was OK."

Honda rider Toni Elias was less fortunate, falling and suffering a shoulder injury that will keep him out of Saturday's race, and championship leader Nicky Hayden also crashed but escaped injury.

Rossi's team-mate Colin Edwards was quickest in the two practice sessions, with another Yamaha rider, Carlos Checa, also on a Yamaha, second fastest.

Sete Gibernau is already out of this week's race after crashing last weekend.

Rossi was lucky to avoid the horror crash which marred the start of last Sunday's Catalunya Grand Prix, in which Gibernau broke his collarbone.

Marco Melandri and Loris Capirossi should be fit to start in Assen on Saturday, despite suffering injuries in the same incident.

Rossi, who is looking for a third consecutive win this season, is also seeking a third win in a row at Assen.

The Dutch race is the second of three successive weekends of racing, and speaking after last weekend's accident, Rossi warned a crowded schedule was threatening riders' health.

"Now we have three consecutive races and this is a problem," he told Motorcycle News.

"We've asked before not to have this, because if you have one problem at the first race then you risk not being able to ride for two more races.

"By the third race the riders are tired mentally and physically, and begin to lose concentration."

Rossi is currently third in the championship standings, behind Capirossi and American Nicky Hayden.