Can Vietnam convert endeavour into a historic World Cup qualifying win?

Vietnam captain Que Ngoc Hai and his teammates have performed admirably so far in the third round of Asian qualifiers for the 2022 FIFA World Cup, but have nothing to show for their efforts yet following three straight losses. AP Photo/Kamran Jebreili

While no team can be eliminated from contention for the 2022 FIFA World Cup after just four matches in the third round of Asian qualifiers, it is possible that some of the continent's heavyweights could be facing long shots after Tuesday's ties.

- Heartbreak for Vietnam; Japan flatter to deceive again

Ahead of Match Day 4 of the Asian qualifiers, we take a look at the biggest talking points.

Can Vietnam convert spirited displays into results?

Despite three defeats, Vietnam have hardly been embarrassed coming up against stronger opposition in their maiden appearance in the third round of Asian qualifiers.

Qualifying for the World Cup was never truly a realistic objective but there is a sense that it would be a real waste if they were to play out the entire campaign without getting some results.

They came excruciatingly close last week when they came from behind to pull level against China PR with two goals in the final ten minutes, only to concede in the fifth minute of injury-time to lose 3-2.

While Nguyen Quang Hai remains the leading light for the Vietnamese, others such as Nguyen Tien Linh and Do Duy Manh are proving they have what it takes to compete at this level.

They will still head into Tuesday's match against Oman as underdogs but a repeat of their spirited performance against the Chinese could just give them a chance of at least picking up a first point of the campaign.

Will Iran or South Korea gain the ascendancy in Group A?

Given their status as the top highest-ranked teams in Group A, it is not a surprise that Iran and South Korea occupy the top two spots, but what is the buffer they have put between themselves and the other teams is worth noting.

Iran lead the way on nine points with the South Koreans just behind on seven, but no other team in the group currently have more than two points with the remaining winless after three matches.

A draw between the two frontrunners would hardly be the worst result for either, but both will be gunning for maximum points to enhance their prospects of reaching the World Cup once again.

In Tottenham man Son Heung-min, the Taegeuk Warriors have one of world football's biggest names and one who is capable of rising to the occasion, as he did last week with an 89th-minute winner against Syria.

Iran though have a plethora of Europe-based stars to call upon, and the manner in which they grinded out a 1-0 victory over United Arab Emirates last time out highlights their capability to not only perform in style but win ugly too.

Japan face do-or-die mission against Socceroos

As participants of the past six editions of the World Cup, and having been Asia's best performers last time out when they reached the knockout round of Russia 2018, it seems unthinkable that Japan could miss out on next summer's tournament.

But with each lacklustre display, the latest being Thursday's 1-0 loss to Saudi Arabia, that scenario is increasingly becoming reality for the Samurai Blue.

Coach Hajime Moriyasu's continued faith in several trusted campaigners who are not exactly in the best of form -- such as Takumi Minamino and Takuma Asano -- has yet to be repaid and, while there is still plenty of time to get their campaign back on track, Japan's cause in Group B is not helped by the presence of two other heavyweights.

Australia and Saudi Arabia are among just three teams out of the 12 with a perfect record of thus far and are in pole position to automatically qualify from the group.

With the Socceroos in fine form, Japan not only a face tough test on Tuesday but head into the tie knowing that falling nine points off the pace this early in the campaign could eventually prove to be a bridge too far.