Alfa Romeo's Robert Kubica set tongues wagging on day four of pre-season testing, setting a blistering time to top the timesheet in the morning session.
It was a rivalry renewed, almost, as Hamilton and Sebastian Vettel battled for top spot in the early stages, but ultimately Kubica would set the pace.
His 1min16.942 on the C5 tyres shot Alfa Romeo's reserve driver to P1, making it the second time the team have topped a session during 2020 pre-season testing.
P2 would go the way of Alex Albon who overcame a late start to get a 1min17.550 out of his C2 tyres, while P3 would have to do for Hamilton, also six tenths back.
After losing out in the morning duel with Hamilton for top spot, Vettel had a trip into the gravel to lure out the first red flags of the day.
The Ferrari man would go wide and off the Circuit de Barcelona-Catalunya at Turn 8, and despite initially rescuing the slide, he would be sent into a spin when he stepped back on the loud pedal while still trundling over the grass.
Robert Kuica setting the early pace. Image: TeamTalk
There were also interruptions for Williams' Nicholas Latifi as the only rookie on this year's grid suffered further mechanical woes as he ground to a halt on the main straight, triggering the red flags for a second time this morning.
Like Albon Pierre Gasly also had issues that kept him in the garage for most of the morning, but once he did get out there with under an hour to go he was able to put his AlphaTauri in P4.
Lance Stroll delivered a solid 43-lap stint as he went for a spot of lunch with his Racing Point RP20 in P5, while Vettel finished his eventful morning in P6.
Daniel Ricciardo was as high as P4 for Renault at one stage but P7 had to do, while Carlos Sainz's running was limited with McLaren forced to take the floor off his MCL35 - P8 was the best he could manage.
The seemingly cursed Latifi and Romain Grosjean completed the top ten for day four's morning session.