Jack Miller's presence in the first MotoGP test of 2016 is in doubt after he was injured in a training accident in Spain on Sunday.
The Marc VDS rider crashed at the Bellpuig motocross track and sustained fractures to both the tibia and fibula in his right leg.
The Australian underwent surgery this morning in Barcelona and will remain under observation for the next 48 hours.
Marc VDS said a decision on whether Miller will take part in the Sepang test next month will be taken closer to the date.
"Jack was unfortunate to sustain an injury so close to the start of pre-season testing, but riders need to train and there is always some risk when you train on the MX bike," said team boss Michael Bartholemy.
"The good news is that the injury is not quite as severe as we first thought and that the surgery was successful.
"For a normal person the recovery period after such an injury would be long, but racers aren't normal people and I'm sure Jack is keen to get back on a bike as soon as possible.
"What is important now is that we monitor his recovery and that he rides again only when he is fit enough to do so, even if that means him missing the first of the MotoGP pre-season tests in Sepang."