Max Verstappen posted the fastest time in the rain-hit first practice session of the Malaysian Grand Prix on Friday, placing ahead of Red Bull teammate Daniel Ricciardo in a reversal of last year's race result.
Red Bull carried over its speed from practice and qualifying at the Singapore GP two weeks ago, impressing on the wet Sepang circuit.
On the eve of his 20th birthday, Verstappen was .757 seconds faster than Ricciardo, whose confidence is high following seven podiums in 10 races.
P1 was delayed by about 30 minutes after a heavy downpour but ended in dry and warm weather. A second practice was scheduled for Friday afternoon.
In a boost for struggling McLaren, Fernando Alonso placed third ahead of Ferrari's Kimi Raikkonen.
Championship rivals Sebastian Vettel (Ferrari) and Lewis Hamilton (Mercedes) were fifth and sixth respectively.
Hamilton has won the past two races and leads Vettel by 28 points, with five GPs left after Malaysia.