Mercedes' Russell the star of Sao Paulo's Saturday sprint as Sainz finishes second
The 100-km race set the grid for the main event at Interlagos, with Brazil the penultimate Grand Prix of the season, but also carried important points for some of the top eight finishers.
It turned out to be a 24-lap thriller, possibly the best sprint to date, with the Brazilian crowd treated to wheel-to-wheel racing, overtakes and clashes between teammates.
"That's how we roll, baby," shouted Russell, who had started third and powered past Max Verstappen (25) on the 15th of 24 laps after a thrilling wheel-to-wheel chase, over the radio as he took the chequered flag.
It was the Briton's first victory in Formula One, even if he is still waiting for a full one.
"They all count," he said. "It was definitely a sweet feeling to cross that line in first position... it's so great to see the progress we're making as a team.
"It's such a morale booster going into the winter regardless of the outcome tomorrow. This is a huge result for us."
Ferrari's Carlos Sainz (28) finished second at the chequered flag but will drop back due to a five-place penalty for exceeding his season's engine allocation.
That promoted Hamilton from third, but race stewards were looking into a potential infringement at the start although Mercedes were confident they were in the clear and back with a bang.
VERSTAPPEN FOURTH
Max Verstappen (25), who lined up on the front row at Interlagos alongside first-time pole-sitter Kevin Magnussen's (30) Haas, finished fourth but will also move up a place and remains a threat.
He complained of running over debris and made contact with Sainz's Ferrari as the Spaniard overtook aggressively with five laps remaining.
Hamilton, who started eighth, also went past the Dutchman.
Verstappen was the only front-runner to start on the medium tyres, with Russell on softs, and that seemed a mistake by a driver who has won a record 14 Grands Prix this season and both previous sprints.
"At the time I felt alright, it somehow didn't work but even on a soft I think I was going to be too slow," he said. "Really, we just had way too much (tyre) degradation here today.
"I'm not sure if we can do a lot for tomorrow, but it can't be worse than today."
Red Bull and Verstappen have already won both championships and are now chasing records, with the team on a run of nine wins in a row.
Mexican Sergio Perez (32), Verstappen's teammate, finished fifth with Ferrari's Charles Leclerc (25) sixth and McLaren's Lando Norris (22) seventh.
Magnussen, who secured an astonishing pole in Friday's qualifying, took a point for Haas in eighth after being passed by Verstappen on lap three and dropping steadily down the order.
"It was always going to be unrealistic to keep those guys behind," he said. "I didn't want to try even because I knew the battle was going to be around P7 or P8. I didn't want to lose any time getting overtaken."
Alpine's Fernando Alonso (41) and Esteban Ocon (26) clashed early on, with the Spaniard finishing 15th after being forced wide and needing a new front wing and the Frenchman 18th.
"I lost the front wing thanks to our friend," said Alonso, who is leaving for Aston Martin at the end of the season.
That team had their own battles with Lance Stroll (24) forcing four-time world champion team mate Sebastian Vettel (35) onto the grass and collecting a 10-second time penalty. The Canadian finished 17th, and Vettel ninth.