A late goal from teenage substitute Divock Origi gave Belgium a hard-fought Group H victory over Russia at a sun-kissed Marcana Stadium Sunday.
The 19-year-old striker pounced on Eden Hazard's cut-back to drive the ball high into the net past Igor Akinfeev, sending Marc Wilmots' team into the last 16 of the World Cup with a game to spare.
In Sunday's second Group H fixture, Algeria overcame South Korea 4-2 in Porto Alegre for its first World Cup victory since defeating Chile in Spain 1982.
The results mean Russia, Algeria and South Korea all still have a chance of progressing to the second phase alongside Belgium, with the final round of matches on Thursday.
Belgium 1-0 Russia
In what was largely a tepid and tame match, Belgium controlled much of the possession -- although it was Russia who had the better of the early play and chances.
Victor Fayzulan's low drive from the edge of the box was saved by Thibaut Courtois as the sides sized each other up early on.
Alexander Kokorin missed a glorious chance for the Russians just before halftime when he headed wide unmarked from only eight yards out.
Fabio Capello's men felt they should have had penalty earlier in the half after Maksim Kanunnikov tumbled under the challenge of Tony Alderweireld but the referee adjudged the Russian midfielder to have stumbled over the ball.
If the first half was starved of chances, the second half was famished. There was little of note until the last 15 minutes when the Belgians began to press
Kevin Mirallas drilled a free kick from 25 yards low against Akinfeev's right-hand post before Hazard had a shot deflected narrowly wide after displaying some nifty footwork inside the Russian penalty area.
But just as a draw seemed likely, the Chelsea star again weaved some magic to set up Origi -- who had come on in the second half to replace the ineffectual Romelu Lukaku.
The late strike also marked the first time a teenager has scored at a World Cup since Lionel Messi did so for Argentina against Serbia in 2006.
"It was a highly tactical game," a satisfied Wilmots told reporters after the match. "We were fresher, we were better and that made the difference -- maybe due to our very good fitness preparations."
With qualification now guaranteed, the 45-year-old also hinted at resting players for the final group match against South Korea Thursday.
"We want to be number one in the group but if there are yellow cards or for reasons of freshness I may make a decision," said Wilmots, who is Belgium's all-time leading scorer at the World Cup with five goals from the three tournaments he played at from 1994-2002.
Capello, meanwhile, lamented what he saw as his side's hard luck in his post match comments.
"The truth of the matter is we had chances to win it but we lost. Both teams gave it their all and unfortunately it was Belgium that was able to make it," the Italian said.
"We have to look forward and I said when we came to play in this World Cup after being absent for 12 years that this will be a great help for us to understand the level we need to be at in future competitions."
Algeria 4-2 South Korea
The Desert Foxes picked up their first World Cup victory in 32 years after a three-goal first-half blitz at Estadio Beira-Rio.
Man of the match Islam Slimani, defender Rafik Halliche and forward Abdelmoumene Djabou gave the North Africans a convincing lead as they overpowered the 2002 semifinalist.
Son Heungmin pulled a goal back for South Korea at the beginning of the second half before Yacine Brahimi -- who switched allegiance from his native France last year -- restored Algeria's advantage with a tidy finish after a one-two with Slimani on the edge of the area.
South Korea captain Koo Jacheol then pulled another back with 18 minutes remaining, but Algeria held on for the historic win.
Coach Vahid Halilhodzic, who guided Ivory Coast to the last World Cup but was fired before it started, knows his team can reach the second round for the first time by beating Russia on Thursday.