The forward went down clutching his hamstring with barely a minute on the clock and was eventually substituted in Saturday's 1-1 draw with Tottenham.
Sanchez Flores said: "I was talking about him in the last press conference about how he's fighting with this injury.
"We know he's happy to be with us, with the team. During the week he was good.
"He didn't complain about anything and our feeling with him was really good, but the ankle is uncomfortable."