Juventus' ex-Bayern Munich striker Luca Toni on Thursday revealed how coach Louis van Gaal once proved he had 'the balls' to drop any of Bayern's stars - by dropping his trousers.

Having joined Bayern from Fiorentina in 2007, Toni, 33, was Bayern's top scorer in his first season when he scored 24 goals in 31 league games as Bayern won the Bundesliga title.

But he played just four league games under van Gaal before he switched to AS Roma in the January winter break at the start of 2010 and was not one of van Gaal's first-choice players.

"Van Gaal simply didn't want to work with me, he treats players like interchangeable objects," said Toni.

The Italian told German magazine Sport Bild about the time van Gaal proved to Bayern's superstars, including Dutchman Arjen Robben, Germany's Philipp Lahm and Bastian Schweinsteiger how he was man enough to drop any of his players.

"The coach wanted to make clear to us that he can drop any player, it was all the same to him because, as he said, he had the balls," said Toni.

"He demonstrated this literally (by dropping his trousers). I have never experienced anything like it, it was totally crazy. Luckily I didn't see a lot, because I wasn't in the front row."

Toni is not the first ex-Bayern player to criticise van Gaal as former captain Lucio has said the coach was part of the reason he left Munich in July 2009.

"Van Gaal hurt me more than anyone else in football," said Brazil defender Lucio who won the Champions League title with Inter Milan last season.

Van Gaal was criticised last October by Bayern president Uli Hoeness for being hard to work with and ex-captain Mark van Bommel quit the club suddenly last week to join AC Milan with rumours he found it hard to work with van Gaal.

On Wednesday, Bayern chairman Karl-Heinz Rummenigge backed van Gaal by insisting the Dutchman is exactly what the German giants need.

Van Gaal has a contract at Bayern until June 2012.