The striker converted a penalty on 79 minutes after Man of the Match Ali Karimi was brought down by Bahrain keeper Abdulrahman Abdulkarim.
Daei, once Bayern Munich forward, scored his own second and side's fourth one minute from time, taking his tally to 97 goals in 129 internationals.
The 35-year-old collected a superb pass from Asian Player of the Year Mehdi Mahdavikia in the penalty area to beat the hapless Abdulkarim in a man-to-man challenge.
Although the match turned sour in stoppage time due to a 20-man brawl, it was a consolation game for the nine-men Iran as it avenged a 3-1 loss to its Persian Gulf neighbor in 2002 World Cup qualifiers that cost Iran a berth in the finals.
The three-time champion Iran, which had substitute Arash Borhani sent off due to a wild lunge on 71 minutes was reduced to nine men in injury time as Hamburg right winger Mahdavikia received his marching orders from the UAE's referee Al Marzouqi, who also red-carded Bahraini scorer Talal Yusuf.
Croat trainer Branko Ivankovic, who intends to part company with Iran within the next month said, "Again we played the last 30 minutes without one player.
"But Ali Daei showed how important he is to us because he is a leader and a great player. We need him. I don't know how long, it`s up to him. I hope he will play a little bit longer."
Midfielder Javad Nekounam put Iran ahead in the eighth minute when he dispossessed Daei of the ball just behind the box to steer it past the diving Abdulkarim with a low angled shot.
Iran came close to the second on 24 minutes when Mahdavikia fired a cannonball, which was defused by the well-placed Abdulkarim.
Surprising package Bahrain had a good start at the second half, scoring the equalizer three minutes after the interval.
Yusuf curled a free-kick over Iran's defensive wall and keeper Ebrahim Mirzapour's hands.
But Bahrain's lead was too short-lived as the Iranian ace Karimi outpaced his two markers on 51 minutes to latch onto a well-flighted chip from provider Mahdavikia and lob over the advancing Abdulkarim.
The goal was Karimi's fifth in the Asian tournament, helping him tie with Bahrain top scorer A'ala Hubail.
Full-back Yahya Golmohammadi, who turned villain after he missed the deciding spot-kick in Tuesday's semifinal against China found Bahrain's net from close range three minutes later but he stopped punching the air as the referee ruled that he was offside.
Iran was again pegged back as Saleh Farhan tapped in on 57 minutes after Duaij Nasser's header ricochetted off the crossbar.
Although Iran was forced to play the last 19 minutes with 10 men, it possessed the ball and field, scoring two late goals.
Bahrain manager Srecko Juricic lauded his side's qualification for the semifinals.
"I think we can be satisfied with the performance," said the Croatian. "For the moment, I think that is the maximum for Bahrain."
China entertains Japan in an eagerly-awaited final at the 66,161-seater Workers Stadium in Beijing Saturday.
... Payvand News - 8/7/04 ... --