Arjen Robben thinks Jose Mourinho's refusal to play on the defensive at Chelsea was the key to their success.
Mourinho, fired by Manchester United in December, is ready for his negative approach to the game since he left Stamford Bridge for the first time in 2007.
In an interview with the Mail on Sunday, Robben says it was the 56-year-old offensive mentality that made him so famous when he first came to England.
The Dutchman joined Chelsea from PSV Eindhoven for 12 million pounds in 2004 and won back-to-back Premier League titles under the guidance of the Portuguese boss.
Bayern Munich star Robben also won a silver medal and a England Cup during his stay in West London.
"I think we were very offensive," he explained. "We played with two strikers, with two wings.
"It was like a 4-4-2, a lot of offensive players on the field, but what I remember from that period is the team.
"It was a real team all together, the players the characters fit together very well.
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"We also had an excellent manager at Mourinho, who made sure that the team spirit is working well and, of course, for the club it was the first time we won the championship in 50 years.
"For me it was a big step, because I was still very young, I was 20. It was the first time I went abroad.
"You have to adapt quickly and especially if you're so young, you have to grow up very fast."
Robben, whose decade in Bayern will end in the summer, spoke last year when his relationship with Mourinho started to get cold.
"For a manager, it's difficult if a player is injured because you can not count on him, so I could understand him a little bit," he said.
"But it's worse for a player – you want to enjoy your football.
"Jose is a winner and wants strong players, I felt a lot of confidence from him when I was in shape, but injuries created a bit of difficulty."