Stoke City midfielder Charlie Adam has backed his club in making it "difficult" for Marko Arnautovic to leave this summer.

The 28-year-old handed in a transfer request on Monday during the club's pre-season tour of Switzerland, having reportedly "grown increasingly frustrated" with life at Mark Hughes's side.

The club have since confirmed that they have rejected a bid of £15m from West Ham United for the winger as they attempt to convince him to stay.

"Marko's a massive figure at the club, I'm going to say it from the players' point of view," Adam told reporters. "He's a wonderful player and he's done a great job for us but something has changed and he's made a decision.

"He wants to look after his family. The club have a say in it and won't make it easy for him, which is right, you can't just turn up, hand a transfer request in and expect to leave. The club will make it difficult for him.

"He's our best player. It's a shock but the club will deal with it in the right way and the manager will deal with it in the right way."

Arnautovic has been at Stoke for four years, scoring 26 goals in 145 appearances.