Schalke’s players had trouble sleeping after a 5-0 demolition by Bundesliga leaders Bayern Munich in a friendly this week, midfielder Roman Neus-taedter said.

“We thought about it a lot and could not put this game aside easily,” Neustaedter told reporters.

“Many of us slept very little that night after the game (on Tuesday) because we were extremely angered by our performance.”

Schalke, who have dropped to seventh at the halfway mark, 17 points behind Bayern, sacked coach Huub Stevens and brought in Jens Keller in mid-December in a bid to turn around their fortunes.

A weak first-half performance in Qatar, when Schalke conceded four goals, triggered the ire of club bosses and sports director Horst Heldt paid a visit to the dressing room at half-time.

Heldt, who said club boss Clemens Toennies called him straight after the game demanding an explanation, said Schalke needed to strengthen their squad, especially after the longer-term injuries of Ibrahim Afellay and Christoph Moritz.