Felipe Massa has said that he thinks Formula 1 drivers will be tested physically in 2017.
That is despite the fact that the sport's new era, characterised by the much faster cars of 2017, kicked off with every driver except the recently-injured Pascal Wehrlein coping physically in Australia.
However, F1 veteran and Williams driver Massa said Melbourne was not the best example of what is to come this year.
"There will be harder circuits," he told Brazilian broadcaster Sportv. "Australia is not very difficult on the physical side.
"But in Malaysia it will be very hot, for example. There are circuits on which we will feel it on the physical side, and if you get tired, the chance to make a mistake is greater.
"I finished the race in Australia well, but without doubt it's harder than before.
"But if you look at the drivers, everyone is training. Most of the drivers are very professional - maybe [Lewis] Hamilton a little less."
Next up on the calendar is the Chinese Grand Prix next weekend.