Loris Capirossi's 200th premier-class race ended at the first chicane in Sunday's San Marino Grand Prix at Misano, when the Rizla Suzuki rider was hit by Ducati's Nicky Hayden.
Both riders fell in the incident, which occurred as they accelerated out of the second apex.
Capirossi was out on the spot, while Hayden rejoined before also retiring due to gear lever damage.
While Hayden was unhurt, Capirossi suffered an injury to his right little finger and will require surgery in San Marino on Monday.
The Italian is hopeful that he will make the next round of the MotoGP championship at Aragon on September 17-19.
“I am very angry at what happened today because I was feeling very confident and the bike was good, so I thought we could have a competitive race," said Loris. "Now I have to have an operation and I hope I can be back for Aragon, but this is nothing compared to what happened in the other race."
Hayden, who had qualified just 14th, has not managed to complete a race at Misano since the venue returned to the MotoGP calendar in 2007.
The American, who has twice previously been the victim of first lap Misano accidents, felt it was simply a racing incident.
"This hasn't been a great track for me over the last couple of years. I got quite a good start and made up some positions but on the exit of turn two when I got on the gas and opened up for the next turn I touched with Loris, who was closing his line a little," said Nicky.
"I'm sorry but it was a racing incident that can happen at any time and when you start so far back you tend to cross lines. The shifter was damaged and I had to come back in."