Schalke winger Jefferson Farfan is set to undergo knee surgery and could face several months out on the sidelines.
Persistent knee problems limited the Peru international to just 19 Bundesliga appearances for the Royal Blues last season.
And on Tuesday, as Schalke began their summer preparations for the 2014-15 campaign, the club's sporting director, Horst Heldt, said that Farfan could now be out until the autumn with an operation looming.
"Also at the request of Jefferson Farfan we tried to treat the knee injury conservatively," Heldt told reporters at the side of the club's first training session. "A German physiotherapist joined him during his holidays, and documented everything.
"It just did not get better. We'd now like to think that he needs to undergo surgery, and that we will have to do without him for a longer period of time, right into the autumn. Jeff is a top player, and has shown how valuable he is for us. But we have also shown that we can win without him."
Schalke, who finished third in the Bundesliga last term, kick off the new season at Hannover, before hosting reigning champions Bayern Munich.