Max Verstappen was back on top in Barcelona as he topped the testing timesheets days after securing his maiden Formula One win at the Circuit de Catalunya.
The Red Bull driver - who became the youngest F1 race winner on Sunday - was back in the cockpit after sitting out the first two days in Spain, completing 118 laps for his new team.
With a set of soft tyres and an updated Renault engine the Dutchman clocked the fastest time of the day at one minute and 23.267 seconds during the morning session, comfortably faster than his nearest rival Stoffel Vandoorne.
Verstappen was delighted with the performance of the new power unit and hoped to see it onboard soon - possibly at the next race in Monaco on May 29.
"I think it is positive. I think mainly we just wanted to check the numbers and the reliability and it was all good," Verstappen is quoted as saying by Motorsport.com.
"We didn't have any problems so we could run the whole day. We tested a lot of things. It all looks very positive.
"I think we have a good chance [of seeing it] there [in Monaco], but first we have to build it up slowly and then we will see where we end up."