Eastbourne Eagles fear Georgie Wood could be ruled out for six weeks with a knee problem.
But the blow has been softened by new team-building averages.
Wood tore cartilage in a fall during the 56-36 win over Coventry 11 days ago.
Initial fears focused on the possibility of a broken collarbone as he fell heavily on his shoulder.
But the cartilage problem came to light after he noticed lack of movement in his knee in subsequent days.
Wood, a renowned grasstracker, has been a revelation at reserve in his first season riding speedway.
His absence comes as his increased average moves him into the main body of the team, giving Eagles far more scope to adequately replace him.
He will be covered by rider-replacement at home to Kent in the Knockout Cup on Saturday (7.30pm) while Martin Knuckey of Coventry guests for Richard Andrews, who is still out with a thumb injury.
Mattie Bates drops to reserve under the new averages. He will be partnered by Kelsey Dugard, who has been recalled to the side in place of Gary Cottham.
Eagles will know more about their line-ups for subsequent fixtures after Andrews has had a check-up next Tuesday.
Chairman Martin Dugard said: “Georgie could be out for four to six weeks.
“When I first saw the crash I thought it would be a broken collarbone or a shoulder injury. He never even moaned about the leg.”
All riders other than Bradley Wilson-Dean and Ben Hopwood are eligible for an extra ride in Wood’s absence.
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