Iran captain Karim Bagheri is remaining cautious ahead of the Asian Cup qualifying contest with Singapore in Tehran on Wednesday.
Team Melli enter the opening Group E contest as the overwhelming favourites to clinch a place in Qatar in 2011, but Bagheri has urged his side not to be complacent.
"People think it's going to be a one-sided match but it's going to be more difficult than that," said the midfielder. "We mustn't underestimate them and we need a good performance against Singapore and then Thailand before our extremely difficult World Cup qualifier against South Korea."
Singapore reached the semi-finals of last month's Asean Football Federation Suzuki Cup, but coach Raddy Avramovic is aware his side enter the fixture in Tehran as underdogs.
"Iran are a physically very strong and compact team, and have very fast, attacking individuals," said Avramovic. "We'll have to keep them out of our penalty box, and disrupt their passing game."
Jordan host Thailand at Amman International Stadium in the night's other Group E fixture.
Coach Peter Reid is targeting a "perfect start" to Thailand's quest for a place in Qatar.
"I have got some information about Jordan and I feel that we can have a good match," said the Englishman. "I believe that we can get a good result which will be a perfect start to our campaign.
"Jordan have not won for five games and I hope that Thailand will be the next team to beat them."
Reid will continue with the players who lost the AFF Suzuki Cup final to Vietnam and is optimistic ahead of the clash.
"We have good players and they can beat Jordan," he added.
Coach Nelo Vingada hopes his Jordan side can upset the visitors.
"I'm optimistic that we can have a good start to our campaign in the qualifiers against Thailand," he said. "It is very important to get a win on Wednesday especially because we will be playing at home and in front of our fans."