Italy left it late to see off Slovenia 1-0, second-half substitute Giampaolo Pazzini scoring five minutes from time to hand the Azzurri all three points in Florence.
The victory leaves Italy unbeaten in Group C and eight points clear of nearest rivals Serbia, who beat the Faroe Islands 3-1.
Milan Jovanovic and Zoran Tosic put Serbia two up and, though the Faroes stunned their more illustrious hosts with a Frodi Benjaminsen strike eight minutes before the break, Zdravko Kuzmanovic wrapped up the victory.
Northern Ireland's hopes were reduced to tatters in Tallinn as a series of individual mistakes left them on the wrong end of a humbling 4-1 defeat by Estonia.
In a game littered with defensive mishaps, woeful lapses in concentration from goalkeeper Lee Camp and defender Gareth McAuley were responsible for two of Estonia's four goals, scored by Martin Vunk, Tarmo Kink, Sergei Zenjov and Kaimar Saag, with the consolation effort coming only when Raio Piroja put the ball past his own keeper.
Spain eased to a 6-0 win over Liechtenstein to seal top spot in Group I, moving eight points clear of the Czech Republic with just two games remaining.
Alvaro Negredo and David Villa scored twice apiece, either side of goals from Xavi and Sergio Ramos, to ensure the reigning world and European champions will be present in Poland and Ukraine.
Steven Naismith earned Scotland a 1-0 win over Lithuania in the other game in the group.
Holland stretched their 100% record to eight games with a 2-0 win over Finland in Helsinki. Kevin Strootman and Luuk de Jong scored for the visitors, while the Finns had Perparim Hetemaj sent off on the hour.
However the Dutch have still not mathematically qualified from Group E after Sweden coasted to a 5-0 win in San Marino. The Swedes remain second on goal difference over Hungary, who won 2-0 in Moldova, and who have played a game more.
Nicklas Bendtner scored twice as Denmark moved into contention for a qualifying place with a 2-0 win over Norway.
Bendtner's first-half double in Copenhagen sent the Danes into second place in Group H, on the same number of points as leaders Portugal and the Norwegians, who have played a game more. Elsewhere in Group H, Iceland claimed their first win of the campaign as Kolbeinn Sigthorsson's strike saw off Cyprus.
Group B remains up for grabs after the Republic of Ireland held on for a goalless draw in Moscow which leaves the Russians two points clear at the top with two games left to play.
The rest of the group was blown wide open by Armenia's stunning 4-0 away win in Slovakia, which draws the Armenians level with the Slovaks in third place, one point behind Giovanni Trapattoni's men. Macedonia defeated Andorra 1-0 in the other Group B match.
Group D leaders France were held to a drab goalless draw by Romania in Bucharest and now sit just a point clear of second-placed Bosnia-Herzegovina, for whom Zvjezdan Misimovic earned a late 1-0 win over nine-man Belarus in Zenica. Elsewhere in Group D, Luxembourg defeated Albania 2-1.
Croatia jumped to the top of Group F after coming from behind to beat Israel in Zagreb while Greece, who started the night on top, needed a late equaliser to scrape a draw in Latvia.
Tomer Hemad gave Israel a 44th-minute lead but after Luka Modric's 47th-minute equaliser the Israelis had Tal Ben Haim sent off and were punished by two goals in as many minutes by Eduardo as the Croatians claimed a 3-1 win.
Meanwhile Greece were labouring in Latvia where Kiriakos Papadopoulos fired home six minutes from time to claim a 1-1 draw. The fate of the group is likely to be settled when Greece host Croatia next month, with both assured of at least a play-off.
Malta and Georgia played out a 1-1 draw in the other Group F clash.
Ashley Young's 35th-minute strike nudged England past Wales at Wembley and left Fabio Capello's men in full control of Group G, now six points clear of second-placed Montenegro.
Xherdan Shaqiri scored a hat-trick as Switzerland kept up the chase for a play-off berth with a 3-1 win over Bulgaria in Berne. The visitors had taken an early lead through Ivan Ivanov.
Arda Turan's missed penalty in injury time blew Turkey's chance of laying claim to second place in Group A as they were held to a goalless draw in Austria. The Turks are now two points clear of Belgium with two games to play.
Azerbaijan defeated Kazakhstan 3-2 in the other Group A encounter.