Fulham are preparing to sell Sascha Riether.
The Daily Star says Schalke general manager Horst Heldt has confirmed their interest this week with the Bundesliga club now preparing to test Fulham's resolve with a bid.
Riether was named players' player of the season and Fulham moved quickly to turn his loan into a permanent switch for around £1.3m last month.
But his form also alerted Schalke.