Max Verstappen completed a practice double for the Styrian Grand Prix as Valtteri Bottas spun in the pit lane.
Verstappen, who leads Lewis Hamilton by 12 points ahead of the eighth round here at the Red Bull Ring in Spielberg, followed up his fastest effort in the first running by finishing quickest in the concluding running of the day.
The Dutch driver was three tenths ahead of McLaren's Daniel Ricciardo, with the Alpine of Esteban Ocon third. Hamilton was fourth, 0.384 seconds adrift of his championship rival.
Hamilton's team-mate Bottas was given a three-place grid penalty for "dangerous driving" by the FIA after he bizarrely lost control of his Mercedes in the pit lane.
The Finn, already 72 points off the pace in the championship, spun after he pulled away from his garage. He narrowly avoided the pit wall before coming to a standstill next to the McLaren garage.
The McLaren pit crew assisted Mercedes in helping a red-faced Bottas recover from his curious predicament, but then complained to FIA director Michael Masi.
"Michael, that's absolutely ridiculous," said McLaren team manager Paul James. "He could have taken our guys out there, and the pit wall." Masi was in agreement, with Bottas called to see the stewards.
Mercedes have dominated Formula One, winning the past seven drivers' and constructors' championships.
But they are facing a stern examination of their credentials, with Verstappen's triumph at Circuit Paul Ricard last Sunday Red Bull's third in succession.
On the evidence of the action at the Red Bull Ring, the Dutchman remains the man to beat, but Hamilton will draw some comfort from posting a time quicker than his rival, despite it being deleted after he ran wide at Turn 10.
But Hamilton fears Verstappen will be hard to beat at a venue where the 23-year-old has won on two occasions.
"It is a work in progress," the seven-time world champion said. "The track is awesome. We are little bit down over a single lap but the car has felt relatively solid.
"However, we are losing a considerable amount on the straight so we have to keep working to rectify that.
"It is very close with the whole pack but the Red Bulls will definitely be very hard to beat. They have got the edge, maybe more, and we don't know what they are going to do when they turn their engine up.
"But I didn't have too many problems today and I am happier with where we got the car to.
"I have been working flat-out all week trying to understand where I want to put the car and I am hopeful the hard work will start to pay off. I will do everything I can to make the right steps this evening."
Double world champion Fernando Alonso finished fifth for Alpine ahead of the Aston Martin of Sebastian Vettel.
Lando Norris, an impressive fifth in the standings following a strong start to the season, ended the day in seventh, half-a-second off the pace.
