The Spaniard has been a key man for the club, scoring their last five goals in all competitions.
But Perez came off with a bruised hip against Brighton in the last game. It is possible he could be back, with Perez himself saying he wants to play as soon as possible.
He said to reporters after the Brighton game: "I'm in pain right now and it's very sore. I got a kick in the hip an I couldn't run any more.
"I'm desperate to be fit for the Liverpool game. That's in my mind right now; to get ready and fit for that game.
"Hopefully it's just a kick that can be helped with a bit of ice and some rest, and then I'll be ready for it."