No-one predicted a Mercedes victory at the start of a race that many in F1 expected to devolve into a fight between the McLaren drivers and Verstappen, even though Norris and Piastri started fourth and fifth and Verstappen 11th.
But Hamilton moved into second place past Perez on the opening lap and followed Leclerc through the first stint.
An early pit stop on lap 11 put Hamilton into the lead by undercutting his rivals – stopping before them and gaining time on fresher tyres – and he held it until his second pit stop.
Russell stopped for his set of hard tyres one lap before Hamilton, and at that stage was expecting to run a two-stop like everyone else.
But he found that degradation was much less than expected and, as the time of his second pit stop closed in, he said to the team to consider going to the end.
As he pushed on, Russell became more and more convinced of his decision, and he and the team committed.
It appeared initially as if Hamilton would catch and pass Russell, as he closed in quickly on his team-mate.
But overtaking proved to be harder than many expected and Russell was able to keep his place, up the main overtaking zone from the first corner through Eau Rouge and up the Kemmel straight to Les Combes, and he whooped with delight as he took the line.
“The tyre whisperer,” an impressed team boss Toto Wolff said to him over the radio.
Before news of his possible disqualification, Russell said: “We definitely didn’t predict this but the car was feeling awesome, the tyres were feeling great and I kept saying: ‘We can do the one stop.’
“Well done to Lewis, he controlled the race, but a one-two was such a great way to go into the summer break.”
Hamilton said: “We had such a disaster on Friday, the car was nowhere. We made some changes, it was hard to know what it would be like in the wet yesterday, and the car was fantastic today.
“George did a great job going long on the tyres, every stint I had tyres left but the team pulled me in.”