Russell, 68 points behind the 19-year-old Italian after six rounds and with no points from his last two races, went around the sunny Circuit de Catalunya with a best time of one minute 15.679 seconds.
The Briton will now go into qualifying after topping two of the three practice sessions.
McLaren's Oscar Piastri, last year's winner from pole, was 0.214 seconds slower with Ferrari's Charles Leclerc third.
Reigning champion Lando Norris, fastest overall on Friday, was fourth quickest for McLaren, with Lewis Hamilton fifth for Ferrari and Max Verstappen sixth for Red Bull.
Antonelli, who will be chasing his sixth win in a row on Sunday, was slowed by traffic on a qualifying simulation.
"Why do I always get traffic?! I don't understand, everyone always in the lap," he said as he decided to return to the pits after a lap that was compromised early on by the positioning of Aston Martin's Lance Stroll.
He was later summoned to stewards, who gave him a first reprimand of the season.
Stewards reported he had been impeded by Stroll at the first corner, after which he applied the brakes and prevented the Canadian from passing.
"The driver admitted during the hearing that he acted out of frustration and apologised for his action," they added.