Yamaha has confirmed that 2010 MotoGP world champion Jorge Lorenzo will miss this weekend's season finale at Valencia.
Lorenzo is still recovering from plastic surgery to repair damage to the ring finger of his left hand, sustained in Phillip Island three weeks ago.
"Jorge continues to recover well from his surgery but unfortunately not quickly enough to ride to his potential this weekend," said team manager Wilco Zeelenberg. "We look forward to having him with us on Saturday and Sunday to provide support for our replacement rider."
Yamaha test rider and All Japan Superbike competitor Katsuyuki Nakasuga will make his second MotoGP appearance in place of Lorenzo.
“It was a great honour to be chosen to ride for Jorge at Sepang and here at Valencia," he said. "Due to the tragic loss of Marco Simoncelli in Malaysia the race was cancelled. This weekend the track will be new for me but I will try as hard as I can to deliver good results.”
Nakasuga will ride alongside Ben Spies, who is returning to action after pulling out of the Malaysian round due to his accident at Phillip Island.
Lorenzo - already confirmed as finishing second in this year's MotoGP championship – could yet ride in next week's Valencia test.
The factory Yamaha team's rider line-up for the 1000cc test will be confirmed on Monday.