|Ghotbi's future could depend on the result of Wednesday's match [AFP]
Iran could be looking for their fifth coach in 10 months if the team fail to bounce back from a poor run of form to qualify for the Asian Cup.
Afshin Ghotbi is under pressure after Team Melli finished last in a friendly tournament in Qatar this month, after losing an Asian Cup qualifier 1-0 to Jordan in November.
But a Group E win over Singapore on Wednesday would see the three-times champions qualify for the tournament, which takes place in Doha in January 2011.
It would also ease the pressure on new Thailand coach Bryan Robson, who is relying on other results to stay alive in qualifying.
Iran top the group on seven points from four matches, one ahead of Singapore followed by Thailand and Jordan with the top two sides from each group qualifying for the finals in Qatar.
Team Melli lost to the hosts and Mali in the friendly tournament in the Gulf state but finished with a win over North Korea in their final match on Saturday.
"I am happy we beat the tournament champions North Korea in our last match," Ghotbi, who is the third coach since Ali Daei was sacked in March last year, told the Mehr News agency.
"Although we did not get satisfying results in the Qatar tournament we made good assessments of our players' capabilities."
With the games not falling on an official Fifa international match date, Asian heavyweights Australia and Japan have been robbed of most of their European-based players for their away matches.
"We slipped up, but the players know how important this game is and they've been working really hard"
Thailand coach Bryan Robson
Japan need just a point in Yemen on Wednesday to clinch qualification from Group A and coach Takeshi Okada has given 13 players their first call-ups to the squad for the match.
Bahrain can also qualify from Group A if they beat Hong Kong and Yemen fail to beat Japan.
Australia face a much trickier task away to Group B leaders Kuwait, who stunned the Socceroos with a 1-0 win in Canberra last year.
The teams are level on seven points from four matches and both can qualify on Wednesday depending on the result of the other group match between Indonesia and Oman in Jakarta.
In Group D, China can join Syria in qualifying if they beat the West Asian side in Hangzhou.
"We will concentrate on attack in training over the next few days. We've got to beat Syria," team manager Du Wei told Monday's Titan Sports newspaper.
Robson's Thailand face a must-win game in their penultimate match at home to Jordan on Wednesday.
Thailand slumped to a surprise 1-0 home defeat by Singapore in December only four days after beating their Southeast Asian rivals 3-1 away, leaving qualification out of their hands.
Robson then followed that result by coaching the under-23 side to a surprise first round exit in the South East Asian Games last month.
"We slipped up, but the players know how important this game is and they've been working really hard," the former England captain told Reuters.
"It is a must win game but the pressure's not on us any more than the other three teams. They've had bad results when they really didn't want to have bad results."