Rossi "suffered a lot" with unexpected arm pain

The seven-time premier class champion had spent a night in hospital last week after injuring his chest and abdomen in a motocross crash while training.

Rossi, who finished 11th and 12th in the two practice sessions on Friday, expected breathing to be an issue on his return to MotoGP action – but was surprised to be held back by arm pain instead.

“Difficult, difficult day, I have to struggle a little bit because this track, Mugello, with MotoGP, with this [high] temperature, is already very difficult physically if you are at 100 percent,” Rossi said.

“Especially this morning I suffer, I suffer a lot, especially in acceleration, because I have pain to my right arm, to stay on the bike.

“When opening the throttle and you have to stay on the handlebar on the acceleration, with all the power, I had a lot of pain. Sincerely I didn't expect [this], we expected something else, was surprised."

The Italian didn't use painkillers for the morning session but decided to take “very light” medication for FP2.

“This afternoon we work a lot on the arm, we take something - and in the afternoon this was better," he explained. "But it remained very difficult, especially to recover, to make some long runs.

“After five, six laps, it was difficult. But it's Friday, maybe [I'll] improve.”

Vinales crash down to “too hard” front tyre

Rossi's Yamaha teammate Maverick Vinales suffered a heavy shunt in FP2, losing his bike on the kerb at Arrabbiata 2.

The championship leader, who was third-quickest in opening practice while using a soft front, was trying the medium compound when he crashed – and says he was lucky to avoid injury.

“For that crash, I am okay. A bit damaged but okay,” Vinales said. “Luckily I walk away, very luckily because corner's really fast.”

He added: “I didn't have a good feeling on the right side [of the medium front]. I think the tyre was too hard for our bike.

“So I think it was a bit the tyre and a bit me searching for the limit of the bike. There was probably less grip and that made me lose it.”

Both Vinales and Rossi stressed tyre choice would be key for the race, but while the Spaniard said he was satisfied with his Yamaha bike's set-up and his pace on the soft front in particular, Rossi was less positive.

“We have to work on the balance of the bike. I am not very happy, we need to try to make [it] a bit better,” Rossi said.

Additional reporting by Matteo Nugnes and Oriol Puigdemont