Barcelona coach Hansi Flick did not want to speculate about the time Marc-Andre ter Stegen could spend on the sidelines after the injury the goalkeeper suffered against Villarreal.

Barcelona maintained their perfect start in LaLiga by winning 5-1 on Sunday.

However, the win was marred by possibly a season-ending injury of their goalkeeper, who had to be taken off in the first half.

"It looks like a serious injury, he felt it, you could see it on the pitch," Flick told reporters.

Ter Stegen fell badly after jumping for a ball just before half-time and was visibly in pain as he was carried off the pitch on a stretcher.

All of Germany international's weight fell on his right leg.

Ter Stegen injured the same knee, on which he already underwent two surgeries over recent seasons, and another operation could prove to be the end his campaign, according to some reports in the Spanish media.

Asked whether he had already thought of a replacement, Flick said: "I don't like this question right after the game. First we have to see what happens with Marc, he's our captain.

"I'm very sad about what happened. Please understand that I don't want to answer this question. I haven't been able to speak to Ter Stegen."

Robert Lewandowski, who scored twice in the rout, dedicated the win to Ter Stegen.

"We don't know exactly what happened, he's in hospital, but of course we are very sad, and this victory is for him," Lewandowski said.