Mercedes driver George Russell was fastest in final practice in Barcelona, with a Mercedes v McLaren shoot-out likely in qualifying later on Saturday.
Russell, who won the first grand prix of the season in Australia before team-mate Kimi Antonelli won the next five, was 0.214 seconds ahead of McLaren's Oscar Piastri.
Charles Leclerc of Ferrari and McLaren's Lando Norris were third and fourth, followed by Lewis Hamilton and Max Verstappen. Championship leader Antonelli placed only seventh.
The 19-year-old Italian was frustrated by traffic and was investigated by stewards for driving erratically.
World champion Norris was the pick of second practice on Friday after fellow Briton Russell had topped the timesheets in the first session.
Cadillac's Valtteri Bottas spun onto the gravel midway through Saturday's session, causing a red flag. He said his brakes had gone.
Practice is notoriously difficult to judge and qualifying will give more of an indication of pace.
Antonelli leads the championship by 68 points from Russell.
The Barcelona-Catalunya Grand Prix was formerly the Spanish GP but that will now be held on a new Madrid circuit, starting in September.
The Barcelona race will alternate with the Belgian Grand Prix in Spa-Francorchamps from next year, with Spa earmarked for 2027 and Barcelona 2028.
