Kimi Antonelli produced an impressive final lap in the closing stages of final practice to go quickest at the Bahrain Grand Prix in Malaysia.
The title leader was looking more comfortable at Sepang, setting a time of 1:36.302 in his heavily-upgraded Mercedes.
Red Bull's Max Verstappen finished two-tenths behind, with his teammate Isack Hadjar in third.
Russell initially was in second after his flying lap, but finished the session fourth-fastest, over six-tenths off Antonelli's pace.
Ferrari's Charles Leclerc and Lewis Hamilton finished in fifth and sixth. Hamilton said over the team radio that "it felt like a pretty decent lap considering the tyres were not great."
A red flag was waved at the halfway point as there was debris on the track which was tangled around Oliver Bearman's front right tyre on the Haas.
McLaren duo Lando Norris and Oscar Piastri were not competitive during the session and crossed the line in seventh and eighth respectively.
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Antonelli, who leads the drivers' championship by 66 points from Russell, had a much stronger day after he finished in fifth and eighth for first and second practice on Friday.
Alpine's Franco Colapinto and Racing Bulls' Arvid Lindblad rounded out the last two places in the top 10.
Despite Hadjar being part of the front-runners, he will be taking a five-grid penalty for a new power unit part. Lindblad will be starting from the back of the grid for Sunday's race after taking on a new power unit.
Colapinto, who carries a five-place grid penalty following his collision at the Azerbaijan Grand Prix last time out, will move further down the order as he takes his fifth engine change.
Qualifying for the race goes green at 9 a.m. BST.