Lewis Hamilton has been forced to abandon his return to track action after he complained of feeling unwell.
Hamilton was scheduled to complete a full day of tyre testing in Abu Dhabi - the scene of his championship defeat by Nico Rosberg on Monday - but was replaced after only the morning session.
Pascal Wehrlein, the Mercedes junior driver who has raced for Manor this season, was drafted in to take over Hamilton's duties. Hamilton also withdrew from a tyre test in October with a sore foot.
"Lewis felt unwell so Pascal stepped in for the later runs," a Mercedes spokesperson said.
Hamilton, 31, was back at the Yas Marina Circuit only two days after his controversial tactics in the title-deciding race provoked Toto Wolff, the Mercedes boss, to threaten disciplinary action against his driver.