Major Asian football nations Iran, Saudi Arabia and China will face their first hurdles in the path toward Brazil 2014 when they start sudden-death home-and-away qualifiers on Saturday, while Qatar has a challenging task as it seeks to assert its World Cup credentials.

With only five nations given byes through to the third round of Asian qualifying, many teams with legitimate hopes of qualifying for Brazil will be thrust into action in second-round, first-leg games. The higher-ranked teams appear to have comfortable assignments on paper, but some have threatening opponents.

atar faces Vietnam, a nation whose passion for the game generally outweighs its performance but which will be confident after a 13-1 aggregate win over Macau in the first round of continental qualifying.

atar will host the 2022 World Cup and is sparing little expense in trying to rapidly improve its national team, employing new coach Milovan Rajevac, who took Ghana to the World Cup quarterfinals last year.

The Gulf team has just returned from a series of friendlies in Europe to tune up for Saturday's game: losing to Lausanne and Bayern Munich and drawing with Neuchatel Xamax, before returning home for a worrying friendly defeat by lowly-ranked India.

''The coach and players respect Qatar but we do not fear them,'' Vietnam striker Le Cong Vinh said. ''We will try our utmost until the last minute.''

No. 50 Iran is the highest-ranked team forced into second-round qualifying, and will start as strong favorite when it hosts the Maldives.

Nevertheless it would envy the free passage to the third round given to the five teams which performed best in 2010 World Cup qualifying: Japan, South Korea, Australia, North Korea and Bahrain.

Iran had a 1-0 friendly win at home against Madagascar last weekend in a tune-up game.

Neighboring Iraq - Asian champion in 2007- has a marginally more difficult match at home against Yemen.

Iraq last weekend finished as runner-up in a four-nation friendly tournament, losing the final to host Jordan on penalties. Jordan will host Nepal on Saturday in the World Cup qualifiers.

China is another nation expected to advance from its meeting with southern neighbor Laos, though China's national team has made a recent habit of failing to live up to expectations at key moments.

It will be eager to make the most of its home game in the first leg, having seen Laos turn around a first-leg defeat by Cambodia in the first round by scoring six goals at home in the second leg.

''In football, we can't say if a country is big or small,'' coach Gao Hongbo said. ''Maybe everyone thinks China is better than Laos, but we have to remind the players to respect their opponent.''

Veteran Du Wei - one of the survivors of the China team that played in the 2002 World Cup - may be one of those who needs reminding, as he was already looking beyond Laos and toward the end goal of making it to Brazil.

''Coach Gao is focused on qualifying for the World Cup and this match is the beginning of our new way to the World Cup and we will try our best,'' Du Wei said.

''We have the confidence that we can qualify, but this is just the first step. We have to face the third round and the fourth round.''

Saudi Arabia also has home advantage in the first leg when it faces Hong Kong. Having failed to qualify for South Africa 2010 - missing football's showpiece event for the first time since 1990 - the Saudis are under pressure to deliver.

There are 15 second-round ties, with the winners to join the five pre-qualified teams in a third round comprising five groups of four.

The top two teams from each of those groups will then go into a fourth round where there will be two groups of five, from which the top two in each group qualifies automatically for Brazil, and the two third-placed teams go into a further playoff.

It is a marathon qualifying campaign, but one which many of the smaller nations would relish if they get beyond the second round, which will be completed with return legs on Thursday.

Among those entering this weekend with more hope than expectation of being in Brazil in three years' time will be Lebanon and Bangladesh who face each other in Beirut; Myanmar, which travels to Oman; Kyrgyzstan, which has a difficult first leg in Uzbekistan; and the Palestinians who travel to Thailand, which will be playing its first match under new coach Winfried Schaefer.

In other first-leg games: Turkmenistan hosts Indonesia, the Philippines travels to Kuwait, Syria is at home against Tajikistan, Malaysia makes the short journey to neighbor Singapore, and the United Arab Emirates will entertain India in Al Ain.