Northants paceman Olly Stone is likely to miss the rest of the season after damaging an anterior cruciate ligament as he celebrated taking a wicket.
The 22-year-old landed awkwardly after jumping off the ground when he had Worcestershire's Moeen Ali caught behind in the T20 Blast on Friday.
Scans have shown he suffered a "compact knee injury with anterior cruciate ligament and cartilage involvement".
He has now been referred to a specialist surgeon.
After falling, he attempted to finish his over, but collapsed in his delivery stride and was carried off the field at Wantage Road.
Stone had played in three County Championship and three T20 Blast matches for Northants this season, taking six wickets in the four-day format and three in the shorter game.
Meanwhile, batsman Richard Levi is undergoing scans to assess the extent of the shoulder injury he sustained in Monday's One-Day Cup defeat by Nottinghamshire.