Neil Lennon produced a tirade on his Celtic players as they struggled in the first half against German 2.Bundesliga side VfR Aalen last night.
The Hoops fell behind to last season's third division runners-up early in the pre-season friendly before second-half goals from Gary Hooper and Anthony Stokes saved the blushes of the Glasgow giants with Lennon reading them the riot act at half-time.
"The second half was better than the first," he said.
"I gave the players a rollicking at half-time and you could see it acted as a wake-up call for them.
"You could see the lethargy lift from the players and they scored two really good goals.
"I can see a gradual improvement in them."
Celtic now face Dutch powerhouse Ajax, Premier League club Norwich City and Italian giants Inter Milan ahead of their first Champions League qualifier at the end of July.