Home hope Carlos Sainz topped the times for Ferrari in a tight and tense final practice ahead of Spanish Grand Prix qualifying on Saturday.
Sainz led Lando Norris, who as the one-hour session came to an end, was inexplicably clipped by Charles Leclerc in the other Ferrari triggering an investigation by race stewards.
Sainz set a fastest lap of 1min 13.013sec to best Norris by 0.03sec, Leclerc, Max Verstappen's Red Bull and George Russell for Mercedes.
Russell's teammate Lewis Hamilton, who had topped Friday's practice, also had a date with the stewards after an incident involving the Aston Martin of Lance Stroll who appeared to deliberately drive into the seven-time champion.
The stewards gave Stroll "a reprimand" for erratic rather than dangerous driving.
"The driver of Car 18 (Stroll) stated that he got impeded by Car 44 (Hamilton) into Turn 5 and that upset him.
"He admitted that he wanted to express his displeasure to the other driver by pulling over on him at the exit," an FIA statement ruled.
The top four were split by less than a tenth of a second opening up the possibility of a thrilling four-team fight for pole for this 10th round of the season later.
Norris was sitting pretty in second as the session drew to a close when Leclerc surged past him, the man from Monaco then clipping the McLaren despite acres of track room.
"He just drove into me, I think I've got damage," Norris told his team.
Just before qualifying began the stewards announced their ruling on Leclerc. who was arguably fortunate to escape a penalty.
The FIA ruled: "The driver of Car 16 (Leclerc) stated that he got impeded by Car 4 (Norris) into Turn 5 and that upset him. He then had to abort his flying lap and contended that, while trying to get off the racing line before Turn 7, he misjudged the position of his car and made slight contact with Car 4.
"Irrespective of any possible intent, the Stewards consider the move made by Car 16, whilst not being dangerous, to be erratic and therefore issue a driving reprimand in line with precedents."
Fire scare
Hamilton was first out on the sun-drenched circuit in Catalonia, and the Mercedes driver had the track to himself for the first five minutes, until Verstappen emerged from the garage to keep him company.
After an encouraging Friday when Hamilton topped practice he posted a 1:14.178.
The session was 10 minutes old before the two Ferraris emerged out into the circuit.
As Hamilton pitted and Stroll told his team "Can you get me a knee pad prepared for the next run? I have some knee pain."
Russell went fastest from Sainz, at his last home race weekend for Ferrari, and Leclerc.
Norris then went second, following a fire at his McLaren team's hospitality centre as final practice got underway.
"This morning we evacuated our team hub paddock hospitality unit following a fire alert, the team has been safely evacuated while the local fire brigade handle the issue," McLaren reported.
Leclerc was feeling far happier after a sluggish Friday practice, telling his team: "Good job on the car. It is a good step forward" after both upgraded Ferraris failed to finish last time out in Canada.
"Happy to hear that," replied his engineer.
Halfway through the hour-long run Russell remained in control but like Stroll had issues with knee pain resulting from the high speed corners.
Norris climbed to the top of the pile inside the closing quarter of an hour before Sainz delighted the partisan crowd with his chart-topping lap and Leclerc tangled with Norris.
Verstappen, who leads Leclerc by 56 points in the drivers' standings, won his maiden Grand Prix at the circuit in 2016, and is on a three-timer after also winning the race in 2022 and 2023.
AFP