Alonso explains the race with Petrov just before Schumacher was taken out.

Alonso: We were coming out of the pits, with a group of cars coming, and it was quite difficult this pit exit. We went to the DRS detection point quite close all together, Vitaly and me, and we had DRS available. He took the slipstream on me and overtook me. I took the slipstream of him and, with the double slipstream, we arrived 30 km/h quicker than everybody else! We braked too late both of us. I had the luck to be on the run off area and he did not have the luck and found Michael [Schumacher]. One of the cars nearly hit me but I saw in the last moment and avoided the accident, so it was okay.