Daniel Ricciardo has lapped the Circuit de Catalunya faster than all before him but the time set in F1 pre-season testing won't count as an official record.
The Australian's time of 1m 18.047s on the new hyper soft Pirelli tyres lit up the timing screens on the second day of the final pre-season test in Barcelona.
It was faster than anyone since the track was reconfigured in 2007, and well ahead of Mercedes pair Lewis Hamilton (1:18.400) and Valtteri Bottas (1:18.560) who both used the slower ultrasoft tyres.
But it won't count as a record because it was set in testing.
"We're getting there," the 28-year-old Australian said.
"The Mercs still look pretty quick. I think a few tenths is in the tyre. And I guess their qualifying mode, when they decided to use it, will probably be a bit more than ours as well.
The time was more than a second quicker than Hamilton's 2017 Spanish Grand Prix pole position of 1:19.149 for Mercedes, and also quicker than any lap in last year's winter testing.
Ricciardo, who finished 5th in last year's drivers' standings, also topped the lap count with a mammoth total of 165.
"We are in a decent place. We made some good changes to the car today, so I think we are better than we were 12 months ago, let's say that much," he said.
Mercedes technical head James Allison said there was no doubt Red Bull would be battling with his team and Ferrari this year.
"There's still some blurriness, it's still not possible to say for sure whether we've got our nose in front of them or they've got their nose in front of us," he said.
"But you can say it's close."
Sebastian Vettel, who did 171 laps on Tuesday when he was fastest, was drafted in for the morning after Ferrari teammate Kimi Raikkonen felt unwell.
He was fourth-fastest with a 1:19.541 lap set on soft tyres.
Fernando Alonso's McLaren again failed him when it began smoking after 47 laps but the Spaniard shrugged off the issue.
"I'm happy when problems happen in testing, we learn a lot and we are lucky they are minor issues," the two-time world champion said.
The new F1 season starts with the Australian Grand Prix in Melbourne on March 25.