Helder Postiga's ninth-minute winner in Lisbon lifted the Portuguese from third to first in Group F, boosting the chances of football fans seeing Real Madrid superstar Cristiano Ronaldo in Brazil next summer.
While Portugal's qualification is still far from secure, Italy is now four points clear of Bulgaria in Group B with four matches left — three of which are at home — after the Azzurri held on for a draw in Prague following the hot-headed Balotelli's sending-off for two bookings.
On a low-key night of qualifying in the European zone, Belgium and Bosnia-Herzegovina both won to consolidate top spots in their groups but Group H leader Montenegro lost 4-0 at home to Ukraine to put second-place England back in control of its own destiny.
Perhaps the biggest celebrations came in Armenia, where Malta's players held hands and danced in celebration after recording a 1-0 win in the other match in Italy's group — only the tiny nation's second ever victory in World Cup qualifying.
The prospect of Ronaldo, one of the game's best and most entertaining players, not featuring in the World Cup would have been very real had Portugal failed to sink a Russia side coming into the match on the back of four straight qualifying wins.
Ronaldo lacked the sharpness he usually demonstrates at club level so it was left to Postiga to come to the rescue, tapping in Miguel Veloso's free kick at the far post to clinch a huge win for the hosts, who moved two points clear in the group. Fabio Capello's Russia dropped to second but has two games in hand and will still be confident of claiming the one automatic qualifying berth.
Italy will head to the Confederations Cup in Brazil knowing only a major collapse will stop them from being back there next summer, too.
The Italians needed a couple of good saves from Gianluigi Buffon to secure a point after being forced to defend in the latter stages thanks to Balotelli's 72nd-minute dismissal.
"Balotelli was nervous," Italy coach Cesare Prandelli said of the striker, who argued with opponents, fellow Italians and the referee during the match. "It is his problem and he has to cope with that."
"The point is of great importance for us," Prandelli added through an interpreter.
Belgium seized the initiative in Group A by beating Serbia 2-1 through goals by Kevin de Bruyne and Marouane Fellaini and seeing Croatia, which started the night level on points with the leaders, surprisingly lose 1-0 at home to bottom-place Scotland.
Belgium is three points clear with three matches remaining.
Ukraine roared back into qualifying contention by condemning Montenegro to a first group loss in an action-packed game in Podgorica featuring three red cards and four second-half goals.
The visitors went down to 10 men in first-half injury time when Roman Zozulia was given a straight red but Denys Garmash still put them ahead in the 52nd minute. Yevhen Konoplyanka made it 2-0 either side of sending-offs for Montenegro pair Vladimir Volkov and Savo Pavicevic before Artim Fedetskiy and Roman Bezus completed the rout.
Montenegro stayed top but England is two points behind in second with a game in hand. Ukraine is a point further back, with two of its remaining four matches coming against last-place San Marino.
Poland drew 1-1 at Moldova to drop to fourth and dent its hopes of a top-two finish.
Bosnia-Herzegovina and Greece claimed contrasting wins in Group G to keep the race top spot bubbling. While Greece, the 2004 European champions, eked out a 1-0 win at Lithuania, the Bosnians thrashed Latvia 5-0 away with Manchester City striker Edin Dzeko one of five different scorers.
Bosnia-Herzegovina has a three-point lead over Greece with four qualifiers left.
In Group C, Austria threw the three-team race for the runner-up spot behind Germany wide open by beating Sweden 2-1 in Vienna. The Austrians are level on points with Ireland, which eased past the Faeroe Islands thanks to a hat trick on his record 126th appearance by Robbie Keane, with Sweden three points further back but having a game in hand.
Iceland and Albania missed the chance to provisionally climb above Switzerland to the top of Group E by losing 4-2 to Slovenia and drawing 1-1 against Norway, respectively. Switzerland hosts Cyprus on Saturday and can pull four points clear with a win.
Finland beat Belarus 1-0 in Group I through Kasper Hamalainen's 57th-minute goal to keep alive its slim hopes of catching the top two of Spain and France.