The 22-year-old underwent surgery on Saturday and the performing surgeon, Dr Xavier Mir, confirmed that his hand was run over during a training session on a dirt track.
"Marc crashed on Saturday while he was practicing dirt track. Unfortunately the rider just behind him hit his hand," Dr Mir told MotoGP.com.
"This caused a severe displacement of the fifth [little] finger of the left hand.
"It [the displacement] was so bad that he thought it was dislocated – as the finger was out of its place. He tried to put it back into place by pulling on it, but as he heard some noise he figured out it was better not to touch it! And that's when he came to the hospital."
Dr Mir, however, remains confident that Marquez will be able to race at this weekend’s race at Jerez after inserting a titanium plate that will stabilize the fractured finger.
"Treatment during the next few days before Jerez should reduce inflammation, so he can race there," Dr Mir declared.
"It's a shame he got hurt but he was lucky it's the left hand – in MotoGP the clutch lever is not used that much.
"It's mainly used for the start of the race, so this kind of helps us so there's less stress on the injury.
"I can't say he will be 100 percent fit, but we always see riders push their limits so I'm sure he will be able to do well!"