Brighton manager Fabian Hurzeler revealed that Wieffer will be sidelined for several weeks after suffering an accidental injury.

Wieffer was injured in last Sunday’s match against Chelsea. Brighton eventually lost 3-4, and the player, who has made 15 appearances for the Netherlands, was forced off after playing 80 minutes, with Kosta Nedeljković coming on as a substitute. Hurzeler later explained how the injury happened.
Hurzeler said: “Mats was hit in the face by the ball, so he temporarily lost control of his body. It was a bit like a heavy punch in boxing. His legs were in a strange position at the time, and that is how the injury happened.”
Hurzeler added: “Fortunately, it is not serious. He first held his head, then after standing up he touched his knee. That is what the players told me. It was just a strange and unfortunate way to get injured, one of the strangest situations I have seen.”
Wieffer will be unavailable for the next few weeks. Hurzeler said: “We believe Mats will definitely be out until the next international break. It is really unfortunate.”
This means Wieffer will miss the first few matches of the Netherlands team under coach Xavi. It is a setback for Wieffer, as he was included in the World Cup squad last summer and would likely have hoped to show himself to the new manager as soon as possible.
Wieffer will also miss Brighton’s matches against Leeds United, Coventry, Manchester United and Arsenal. After the international break, he could return to the squad for the match against Sunderland on October 10.