Russell had been running strongly in second at Suzuka and was in contention for the win before the race turned on a pivotal moment.
A high-speed crash involving Ollie Bearman triggered a Safety Car just one lap after Russell had made his pit stop, allowing Antonelli – who had yet to stop – to pit under caution and emerge in the lead.
The 19-year-old Italian controlled the race from there to secure his second consecutive victory, becoming the first Italian driver since Alberto Ascari in 1953 to win back-to-back races and the first teenager to lead the Drivers’ Championship.
For Russell, the frustration deepened after the restart. A battery issue left him unable to defend his position, with Lewis Hamilton overtaking before a further loss of power allowed Charles Leclerc through.
Although Russell later reclaimed a place from Hamilton, he was unable to catch Leclerc and finished fourth.
“If it had been one lap difference, then it probably would have been a race win,” Russell said. “That’s frustrating.
“Safety Car timing, and then at the restart I had a harvest limit which meant I couldn’t recharge my battery. I had no battery, Lewis passed me, and then I faced another battery problem when Charles passed me.”
The result leaves Russell nine points behind Antonelli in the standings after three races, despite opening his season with victory in Melbourne.
“At the moment, it is just one thing after the other,” Russell added. “We have not had a single issue in practice, but I have had problems in qualifying instead. It is the luck of the draw with these new cars.”
Despite Antonelli’s rapid rise, Russell dismissed concerns about momentum in the title race.
“It is race three of 22, and I am not concerned at all,” he said. “It is a long year, and I know I have got what it takes to bounce back.
“We have got a four-week break, so there is no momentum to be carried over. We will reset and go again.”
Antonelli, meanwhile, struck a measured tone after moving to the top of the standings.
“I’m not thinking too much about the championship,” he said. “Of course it’s great, but there’s still a long way to go.
“We need to keep raising the bar because George is very quick, and for sure he’s going to be back at his usual level.”
Mercedes have now won all three races this season, with Antonelli’s back-to-back victories establishing him as an early title contender ahead of the next round in Miami.
