Pol Espargaro will be taken to hospital in Barcelona on Saturday for surgery on the left collarbone he broke again during MotoGP FP3 for the Aragon Grand Prix.
The KTM rider initially suffered the collarbone brake in his left shoulder in a heavy fall during the warm-up session at Brno last month, where he also inflamed his spinal cord.
Espargaro missed the Brno race as well as the Austrian and British Grand Prix weekends, but returned to action at Misano last time out – though was unable to finish the race due to his shoulder.
The Spaniard's recovery was dealt a set-back when it was revealed the extent of his collarbone injury had been misdiagnosed, and was wrongly advised against surgery.
While feeling almost back to full fitness this weekend, Espargaro re-broke the collarbone in his left shoulder in a crash at Turn 15 in Saturday morning's FP3 session.
After being taken to the medical centre for checks, he was declared unfit to continue at Aragon, and will head home to Barcelona for surgery in a bid to be fit enough to race in Thailand in two weeks' time.
A short statement on KTM's Twitter feed read: “After a crash at T15 in MotoGP FP3 for the Aragon GP, Pol Espargaro broke his left collarbone again and is declared unfit to race.
“He is on his way to the hospital for an operation today.”
Espargaro's absence comes as another blow to KTM, with the Spaniard now set to miss a test at Aragon next week.
Teammate Bradley Smith, who will be the sole KTM representative for the second race this season, ended this morning's FP3 session 12th and just over 0.040 seconds from a place inside Q2.
It was confirmed during the Misano weekend Smith will join Aprilia next season as test rider, while the retiring Dani Pedrosa is expected to become an official test rider for KTM in 2019.