Cheering fans poured onto the streets of Thimphu on Tuesday as Bhutan, the world's lowest-ranked football team, pulled off a major shock to reach the second round of World Cup qualifiers.

Joyous supporters banged drums and chanted "Now we're not the worst team!" after the tiny Himalayan nation, rock-bottom at 209th in the FIFA rankings, stunned Sri Lanka 3-1 on aggregate.

The "Ronaldo of Bhutan", Chencho Gyeltshen, struck twice in Tuesday's 2-1 win at a packed Changlimithang Stadium, a week after Chokey Nima's men beat Sri Lanka 1-0 in Colombo.

Gyeltshen opened the scoring on five minutes and he was mobbed by his team-mates when he coolly struck the winner in the 90th minute, sealing Bhutan's progression.

Although Sri Lanka are only ranked 174th, Bhutan, attempting to qualify for a World Cup for the first time, were such outsiders that ex-Sri Lanka skipper Ashok Nawgalage even questioned the point of playing the tie.

But in the event it was the Bhutanese -- given the afternoon off by Prime Minister Tshering Tobgay to support the national team -- who were celebrating a memorable win.

Bhutan, better known for its Gross National Happiness Index and archery, will now take its place among 40 Asian teams in the group qualifying stage starting in June.

Although Bhutan's chances of reaching the 2018 World Cup in Russia remain extremely small, they have provided the first upset at the start of a marathon, global qualifying campaign.

It was not the only fairytale result as East Timor, one of the world's youngest and poorest nations, sent Mongolia crashing out 5-1 on aggregate in chilly Ulan Bator.

Sleeping giant India made it through thanks to a 0-0 draw with Nepal in Kathmandu, following last week's 2-0 victory in the east Indian city of Guwahati.

But Pakistan's home leg against Yemen in Lahore was postponed and shifted to an as-yet-unnamed neutral venue after a deadly Taliban attack on churches in the city.

The move was another blow to sport in Pakistan, who trail 3-1 from the first leg, after a 2009 attack in Lahore put tours by international cricket teams on hold.

Elsewhere Taiwan fought back from 1-0 down in the first leg to beat Brunei 2-0 away thanks to goals from Wang Ruei and Chu En-le either side of half-time.

French-born Thierry Bin scored for Cambodia in a 1-1 away draw with Macau, which was enough to seal their progression 4-1 on aggregate.

Asia's lowest-ranked teams were playing home and away to reach the group stage, kicking off a marathon, worldwide qualifying campaign for the next World Cup.