Sebastian Vettel has withdrawn from the opening day of Formula One testing after falling ill.

The four-time world champion was due to kick off Ferrari's pre-season campaign at the Circuit de Catalunya on Wednesday.

But Ferrari confirmed Vettel was "not feeling great this morning" and would not be in action, with team-mate Charles Leclerc assuming driving duties for the Italian team.

Vettel, 32, posed for a group picture with all the sport's drivers ahead of the first day of testing before he was later seen leaving the track.

Racing Point's Sergio Perez was the early pace setter in Barcelona ahead of McLaren's Carlos Sainz and Leclerc.

Defending champion Lewis Hamilton is due to take over from Mercedes team-mate Valtteri Bottas on Wednesday afternoon.

The first test concludes on Friday, with three further days of running here in Barcelona next week.

Hamilton, the six-time world champion, will open his title defence in Melbourne on March 15.