Renault admit Alonso's return in 2008 was a mistake

At the end of his tumultuous single season with McLaren in 2007, Alonso broke his contract to return to the scene of his championship wins. The next two years were barren for Renault and Alonso, and he moved on to Ferrari.

"We know what happened [at McLaren], and he came back," Nielsen said. "I actually think it was probably a mistake. I don't know if he agrees with me but he knows I love him.

"If I had been his manager at the time, I would have told him 'Listen, you have to stay and beat this guy [Lewis Hamilton]'. 'Firstly because you have the best car now, secondly because your best chance to be champion next year is to stay at McLaren."

Source: espn.co.uk