Burnley boss Sean Dyche is upset for Dean Marney over his knee injury.
The 31-year-old, who has played nearly 200 matches in close to five years at Turf Moor, suffered the injury during Sunday's 2-2 draw with West Brom.
The incident appeared innocuous but scans confirmed Burnley's worst fears and an unwanted hat-trick.
Marney joins defender Kevin Long, who suffered the same injury last month, in the treatment room, while striker Sam Vokes missed the start of the season as he recovered from a ruptured cruciate.
Dyche said: "It's amazing that we've had three cruciate injuries in a year and all of them anomalies. Deano thought he might be able to run it off such was his desire to continue.
"We feel for Deano and ourselves because he's done very well over a number of years. We know he'll get the right support here and him and Longy will be good mates over the next few months."