Watford winger Gerard Deulofeu is likely to miss the rest of the season after rupturing his anterior cruciate ligament and tearing his meniscus in the surprise 3-0 win over Liverpool.
The Spaniard had to be carried off on a stretcher after an awkward fall and needs surgery on his damaged knee.
The Hornets are outside the relegation zone on goal difference.
Former Barcelona and Everton winger Deulofeu has scored 17 goals in 70 games since moving to Watford in 2018.
“Unfortunately for him and us, the scan results really show he is probably going to be out for the rest of the season,” boss Nigel Pearson said.
“For sure Geri is going to be a miss for us, but equally it’s important we look forward with a positive mentality. Maxi [Roberto] Pereyra went in for Geri and I thought he did very well when he went on.
“It almost goes without saying that we’ll give Geri all the support he needs for a full recovery.”