Gareth Bale scored the only goal and Wales hung on through the rain to beat Belgium 1-0 and move top of their European Championship qualifying group.
The Real Madrid star controlled on his chest a misguided back-header by Radja Nainggolan, swivelled and side-footed a shot through the legs of goalkeeper Thibaut Courtois in the 25th minute for the winner at Cardiff City Stadium.
The victory over FIFA's No. 2-ranked team gave unbeaten Wales 14 points from six games, three ahead of Belgium atop Group B with four games to play.
With second place enough to a secure a spot at the finals in 2016, Wales are five points clear of Cyprus and Israel in third place.
Remarkably, the victory also earn Chris Coleman's men enough co-efficient points to be guaranteed top seeding for the World Cup qualifying draw later this month.
Also in Group B, Bosnia and Herzegovina defeated Israel 3-1 to tighten the race for third.
Edin Visca scored twice and Manchester City striker Edin Dzeko also netted against Israel, who could only respond through Tal Ben Haim Jr.
Cyprus are also still in contention after easing past Andorra 3-1.
They won thanks to a hat trick from Nestor Mytidis, that allowed them to make light of Junior Dossa Momade's second-minute own goal.
In Group A, Netherlands earned a much-needed 2-0 win at Latvia to revive their qualifying campaign.
Georginio Wijnaldum replaced Robin van Persie in the 63rd minute and scored the breakthrough four minutes later, and his PSV Eindhoven teammate Luciano Narsingh soon doubled the lead.
Iceland moved top of the group with a 2-1 win at home against the Czech Republic, who are second, three points ahead of the Dutch.
Borek Dockal opened the scoring for the Czechs before Aron Gunnarsson and Kolbeinn Sightorsson gave Iceland the win.
Earlier, Tukey boosted their precarious qualification chances courtesy of a shaky 1-0 victory in Kazakhstan.
The visitors moved on to eight points in Group A, Arda Turan firing the winner seven minutes from time.
Defeat leaves Kazakhstan rooted to the foot of Group A with one draw and five losses from their six qualifiers.
Croatia maintained their two-point lead over Italy atop Group H after drawing 1-1.
Mario Mandzukic saw a penalty saved by Gianluigi Buffon before scoring the opener. He also gave away a spot kick which Antonio Candreva converted for the equalizer in the 36th minute.
Neither side could find a winner in a second half where Croatia captain Dario Srna was sent off for a second bookable offence at the death.
However, the game will again be overshadowed by side events as a swastika pattern was clearly seen etched onto on the pitch. The November qualifier at San Siro was temporarily halted by crowd trouble and Croatia had to play Friday's match without any fans as punishment for racist chanting and other misconduct during that 1-1 draw.
Also in Group H, Ivelin Popov fired the only goal to hand Bulgaria a 1-0 victory in Malta.
Popov scored in the 56th minute to hand Bulgaria only its second win of the qualifying campaign. Ilian Micanski had sent a spot kick wide for Bulgaria on the stroke of half-time after Ryan Camilleri impeded Vladimir Gadzhev.
Norway slumped to a 0-0 home draw with Azerbaijan.
Azerbaijan goalkeeper Kamran Agayev pulled off a string of fine saves, while Alexander Soederlund had a first-half goal ruled out for offside and Even Hovland headed substitute Pal Andre Helland's cross off the post with four minutes remaining.
Azerbaijan ended a run of five consecutive away defeats but remained fifth.