Highlights: Croatia 0-1 Scotland
Helder Postiga's goal was enough to propel Portugal to the top of their World Cup qualification group with a 1-0 win as Russia dropped the first points of their campaign.
Russia had arrived in Portugal top of Group F with a 100% record after four games although the build-up to the game had been overshadowed by speculation over manager Fabio Capello's future.
For Portugal, the game was crucial as they lay third behind Russia and Israel with just three wins from six matches.
Postiga's ninth-minute goal proved sufficient to send Paulo Bento's side top, two points ahead of their visitors although Russia - who offered little - have two games in hand.
Robert Snodgrass was the hero as Scotland pulled off a major shock by picking up their first win of the World Cup qualifying campaign 1-0 against Croatia in Zagreb.
Gordon Strachan's men headed into the match already out of the race for Brazil in 2014, massive underdogs to claim a positive result and a staggering 70 places behind Croatia in the world rankings.
But Snodgrass proved to be the difference between the two nations when he grabbed the only goal of the game to hand the Scots their first competitive victory since beating Liechtenstein in October 2011.
Belgium took a major step towards the finals as headed goals from midfielders Kevin De Bruyne and Marouane Fellaini gave the Belgians a fine 2-1 home victory over Serbia, dangerous opponents who were professionally put away.
There were roars at the King Baudouin stadium for both goals, but also when news came through of the strike against Croatia that earned Scotland a surprise win in Zagreb. It means Belgium are three points clear of Croatia at the top of the group.
Ukraine moved firmly into contention with a comfortable 4-0 win in Montenegro which blows Group H wide open.
The visitors had Roman Zozulya sent off in first-half stoppage time but took the lead six minutes after the restart through Denys Garmash. Yevgen Konoplianka made it 2-0 in between the dismissals of Montenegro's Vladimir Volkov and Savo Pavicevic, and Artem Fedetskiy and late substitute Romas Bezus added further goals.
Both teams are battling for a qualifying spot with England, whose manager Roy Hodgson had expressed his hope for a draw given that Montenegro led the group by two points. But victory for Ukraine brought them within a point of his side with two games against minnows San Marino still to come.
Poland suffered frustration in Chisinau as they were held 1-1 by lowly Moldova.
Needing a point to put the pressure on second-placed England in Group H, Poland got off to the perfect start when Jakub Blaszczykowski fired them ahead just six minutes into the match. But they failed to build on it before Eugen Sidorenco levelled in the 37th minute and Poland could not find a winner as Moldova sat deep in the second half.
Austria kept hold of second place in Group C with a huge 2-1 victory over rivals Sweden in Vienna.
Ahead of the visitors on goal difference alone, and having played a game more, Austria's position was more than a little vulnerable going into the match but David Alaba's penalty and a Marc Janko header put them in control. Although Johan Elmander pulled a goal back late on, Austria held on for three vital points.
Robbie Keane celebrated his record-breaking 126th cap with a hat-trick as Ireland eased past the Faroe Islands 3-0 to bank three priceless points.
The 32-year-old claimed his 57th senior international goal with an accomplished finish with just five minutes gone, and then added another 10 minutes after the break from Seamus Coleman's inviting cross. But there was more to come as substitutes James McClean and Conor Sammon teamed up to hand him his third of the night and 59th in total on a plate with nine minutes of the game remaining.
The wins means Ireland are only behind Austria on goal difference, with the two teams five points behind clear group leaders Germany.
Mario Balotelli's dismissal was the talking point as Italy ground out a 0-0 draw with the Czech Republic in Prague.
Three points would have seen Cesare Prandelli's men open a six-point lead over Bulgaria at the top of Group B but, if not for Gianluigi Buffon's heroics in the Italy goal, the Czechs might well have taken second spot and firmly stated their case for automatic qualification.
The Azzurri successfully weathered heavy pressure from a particularly keen Libor Kozak but Balotelli's impetuous dismissal for two quickfire yellow cards threatened to hand their hosts the initiative in the final exchanges.
Malta finally earned their first points of the campaign as they scored early to beat fellow strugglers Armenia 1-0 in Yerevan in Italy's group.
The visitors, defeated in all five of their qualifiers to date, struck after just seven minutes when Michael Mifsud fired into the top right-hand corner of the goal from close range.
Bosnia-Herzegovina scored five second-half goals to finally put away 10-man Latvia 5-0 and strengthen their position atop Group G.
The hosts had Aleksandrs Fertovs sent off early in the game but kept the scoreline goalless until the interval. But Senad Lulic and Vedad Ibisevic struck shortly after half-time and further goals from Haris Medunjanin, Miralem Pjanic and Edin Dzeko made for an emphatic away win.
Lazaros Christodoulopoulos headed the only goal as Greece stayed in the hunt with a 1-0 win in Lithuania.
With four rounds of matches remaining Bosnia are three points clear of Greece, with a far superior goal difference should that become a factor.
But Greece do appear to have the easier fixtures ahead, including home and away games against Liechtenstein, so head coach Fernando Santos can still look up the table rather than consolidating second place and aiming for the play-off route to Brazil 2014.
Liechtenstein claimed just their second point with a 1-1 home draw against Slovakia which left the visitors' hopes in tatters.
Martin Buchel put Liechtenstein ahead in the 13th minute only for Jan Durica to head home the second-half equaliser, but the draw was an unappealing result for Slovakia who started the match third in Group G, two points behind second-placed Greece.
Azerbaijan and Luxembourg are both still searching for their first win after drawing 1-1 in Baku.
Hosts Azerbaijan, having hit the woodwork twice in the opening 25 minutes, took the lead in the battle of Group F's bottom two nations in the 71st minute when Ruslan Abishov headed home Araz Abdullayev's cross from the right. However, that lasted just nine minutes before Stefano Bensi drew Luxembourg level.
Norway put the brakes on Albania's surge towards a first World Cup appearance as Tom Hogli forced a 1-1 draw.
Victory would have seen Albania leapfrog Switzerland to leave Norway struggling in the wrong half of the table, and Valdet Rama's opener certainly gave the Scandinavians food for thought.
But Norway's determination to avoid an embarrassing double defeat to these opponents helped Hogli rescue a point at the death. It means the two nations remain behind Switzerland, who now have a game in hand.
Iceland's hopes of claiming a top-two finish in the group suffered a body blow as they slumped to a 4-2 home defeat to bottom-placed Slovenia in Reykjavik.
The home side would have moved into first place with a victory and they were briefly on course to do so after goals from Birkir Bjarnason and Alfred Finnbogason saw them overturn an early deficit to lead 2-1 with 26 minutes gone.
However, Slovenia made it 2-2 almost immediately through Valter Birsa and then second-half goals from Bostjan Cesar and Rene Krhin earned them a second victory to climb off the foot of the standings.
A Kasper Hämäläinen goal separated Finland and Belarus as the home side edged a battle of the Group I also-rans 1-0 in Helsinki.
With Spain and France running away with the five-team World Cup qualifying group, Finland, Belarus and Georgia have been little more than cannon fodder for the European heavyweights, but this meeting gave two nations a chance to flex their own muscles.
Finland took the points and their first qualifying win thanks to Hämäläinen's 57th-minute goal, which could go down as an own goal for Igor Shitov. Belarus ended up a man down as Pavel Nekhaychik was sent off late on.