Sergio Perez has claimed that Fernando Alonso's racing schedule this year is nigh on "impossible" to manage.
Alonso, having last year skipped Monaco to do the Indy 500, is this year combining the Formula 1 calendar with the full world endurance championship including Le Mans.
"That's a really hectic programme," Force India driver Perez told El Mundo Deportivo.
"With how busy we are, not only with races but also the simulator and everything else that we have to do, I think it's impossible to do.
"You would have to find the perfect compromise with your calendar to achieve it, but I don't think you can do two seasons at once.
"Right now we have 21 races which requires a lot of commitment, so at this point in my career I would not consider it."
The first of 2018's grands prix takes place in Melbourne on March 25.
