France's defence made the difference, on both sides of the field.
Goalkeeper Hugo Lloris kept out the shots and defender Samuel Umtiti scored the winning goal.
It was France's backline, not its slick attackers, carrying the team to the World Cup final with a 1-0 win against Belgium on Tuesday.
No wonder coach Didier Deschamps fell into Umtiti's arms after the final whistle.
His superbly drilled defence, led by an imperious Raphael Varane, neutralized Belgium's much-hyped attack to record a fourth shutout in six games so far.
Umtiti danced in front of the France fans, while his centre back partner Varane walked over to them and pumped his clenched fist.
Varane was injured when France lost the European Championship final two years ago, and he looks determined to make up for it.
The spotlight has been firmly on France's 19-year-old sensation Kylian Mbappe in Russia, whose electric pace and skill lit up the tournament.
But for the second consecutive knockout game, a defender managed to score when he couldn't.
Against Uruguay last Friday, it was Varane's glancing header giving France the lead in a 2-0 win. A few days later, it was Umtiti rising to head home a corner from the right in the 51st minute.
"Enormously proud,'' Umtiti said. "We worked really hard together, and it's me that scored but we all delivered a big game.''
Umtiti showed superb timing to leap above midfielder Maroune Fellaini, the tallest non-goalkeeper on either side, and power a header past Thibaut Courtois guarding Belgium's goal.
Forward Antoine Griezmann set up Umtiti's and Varane's headed goals up with his exquisite, cushioned delivery from set pieces.
But, like Mbappe, he took a back seat against the Belgians as Lloris and his defence starred at St. Petersburg Stadium.
Varane made decisive headers to cut out dangerous crosses and corners and read to perfection almost every run from striker Romelu Lukaku and the fleet-footed forward Eden Hazard.
He also compensated for the times when right back Benjamin Pavard was caught out of position, particularly by Hazard, when Belgium dominated the opening 20 minutes.
When France's defence was breached, the agile Lloris was on hand to make decisive saves _ just like against Uruguay.
He made a superb, leaping stop to his right to palm away a sudden, close-in strike from Toby Alderweireld in the 22nd minute that would have gone inside the left post.
Midway through the second half, Lloris was there again, springing off his line to punch away a dangerous right-wing cross from Belgium substitute Dries Mertens.
With 10 minutes left and Belgium pressing, Lloris flew off his line to his left to push away a powerful shot from midfielder Axel Witsel.
France won its only World Cup 20 years ago, thanks to a commanding goalkeeper, Fabien Barthez, protected by a rock-solid defence.
Back then, France kept five shutouts in seven games. With Croatia or England awaiting in Sunday's final, the formula is one game away from working again.