Sebastien Ogier overcame a boost problem to post the fastest time on the opening stage of the Rally de Portugal on Thursday.
The World Rally Championship leader was 2.6 seconds faster than closest title challenger Hayden Paddon in Lousada, but was unable to hide his concern over the initial technical issue.
"I had no boost from the engine for the first few hundred metres but then it came back," said the Volkswagen driver. "I hope the team can quickly check what it is and solve the problem."
Hyundai's Thierry Neuville, who had gone fastest in the earlier shakedown, was 0.9 seconds down on Ogier in second.
"I'm quite confident," said Neuville. "I enjoyed the stage with all the spectators, it was nice to start the rally like this."
Neuville's team-mate Dani Sordo rounded off the top three, while Andreas Mikkelsen was fourth, despite stalling his Volkswagen Polo R on two occasions.
The rally continues with eight stages on Friday, including two loops of three circuits.