Valentino Rossi revealed he suffered clutch problems before crashing out of the Grand Prix of the Americas on Sunday.
Rossi started from third place in Austin but quickly dropped down the field to sixth before losing the front of his Yamaha at turn two a few laps in.
It was Rossi's first retirement since September 2014 at the Aragaon Grand Prix and the Italian said he was suffering mechanicals problems before crashing out on Sunday.
"Fortunately I'm OK, because that corner is quite fast," the seven-time premier class champion said after the race. "It was a 'good' crash.
"Unfortunately I burned the clutch at the start, and I had a lot of problems in the first two laps, because the clutch slipped a lot, so I have to say half throttle on the straight - so everyone overtook me.
"I tried to stay quiet and concentrated, because I know the clutch usually comes back when it cools down, and in fact it was coming better.
"But I arrived at turn two on the third lap and I lost the front. For me, the bike was normal, for sure I did some mistake: maybe I entered too fast or was a little too much inside.
"It's a great shame because this weekend we worked very well, and I was very competitive.
"I could have done a good race but I did a mistake, and that happens. Apart from the crash, it was my best weekend here in Austin. We can be very strong."
The retirement meant Rossi slipped down to third in the championship standings, 33 points behind leader Marc Marquez and 12 behind team-mate Jorge Lorenzo.