Alex Marquez has given further details of how brother, team-mate and reigning MotoGP champion Marc broke the titanium plate inserted just a week earlier to stabilise his fractured right arm.

Forced to back out of a miraculous early return just days after the initial surgery, Marc then set his sights on a comeback at this weekend's Brno round, posting videos of gym work with the injured arm as recently as last Sunday.

Then, on Monday evening, Repsol Honda suddenly announced that Marquez had undergone a second round of surgery to replace the plate, which had become 'damaged' due to 'an accumulation of stress'.

No further details were given until team manager Alberto Puig arrived at Brno today (Thursday) and revealed that the plate - "probably" weakened from the exertion of attempting to ride at Jerez and following rehabilitation work – had "broken" while Marquez was "opening a window".

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"I live with Marc and it was 7:30 in the morning, on Monday," explained Alex. "Marc woke up a little bit earlier than me, so I was still on my bed and he woke me already with the arm broken.

"He was only planning to go for a walk with the dogs and relax a bit, but opening a big window - it's like a door window - broke the arm. It happened like this.

"He woke me up and also the physio, who was at home to help with [Marc's] recovery, and then they called Emilio [Alzamora] and went directly to the hospital.

"It was a strange situation but it can happen."

Marc is confirmed as missing this weekend's Czech round but is also in major doubt for the following pair of Red Bull Ring races.

HRC test rider Stefan Bradl will replace the #93 this weekend when Alex will be looking to build on his 12-8 finishes at Jerez and also expects to get some advice from Marc watching on TV at home.

"He's my brother and I experienced that [difficult] situation, but nothing changed about how to approach this weekend for me and these three races in a row. The same mentality; try to improve," he said.

"I'm a rookie so every day is important for me. And Marc will say something to me while watching from home, for sure!

"Three races in a row will be hard physically and mentally, but we don’t have so much travelling to do [from Czech Republic to Austria] so I think it'll be better than Japan-Australia-Malaysia. We are riders and we train for this."