The Republic of Ireland enter the white heat caldron of the Azadi Stadium knowing they're just 90 minutes away from qualifying for the World Cup Finals for the first time in seven years, the third time in their history and to a major tournament for the first time under Mick McCarthy.
McCarthy's side must hold their nerve as they defend a 2-0 first leg lead in front of 120,000 vociferous Iranian supporters.
Iran have also played in the World Cup Finals twice before and will be equally keen to fill one of the two remaining berths for Korea and Japan 2002.
The Republic of Ireland are unbeaten in 16 Internationals - 10 wins, 6 draws. Their last defeat was 2-1, away to Scotland in a Friendly on 30 May, 2000.
The Republic have also not conceded a goal in their last three away Internationals - all World Cup Qualifiers (winning 0-2 against Estonia on 6 June, 0-3 against Andorra on 28 March, and 0-4 against Cyprus on 24 March).
Iran have been beaten twice in their last 11 - all World Cup Qualifying Internationals.
Qualification would swell the cash strapped Republic of Ireland FA coffers by an estimated £50 million for just reaching Korea and Japan.
The Republic of Ireland have a play-off jinx to overcome. They have lost four out of four. The first was 36 years ago to the day (matchday) - 10 November, 1965 - when Spain won 1-0 in Paris in the World Cup. The second resulted in a 2-0 defeat by Holland at Anfield on 13 December, 1995 in the European Championship - Jack Charlton's last match in charge. In Brussels on 15 November, 1997, the Republic lost the Play-Off 2nd leg 2-1 to Belgium, after drawing 1-1 in Dublin. Most recently, the European Championship Play Off against Turkey on 14 and 17 November, 1999 was lost on the away goal rule. The Republic drew 1-1 at Lansdowne Road, and then drew the away leg 0-0.
HEAD TO HEAD
MOST RECENT MEETING
World Cup UEFA/Asia Play Off 1st Leg Lansdowne Road, Dublin, 10 November, 2001 Attendance: 35,000
REP OF IRELAND 2-0 IRAN Rep of Ireland scorers: Harte 45 pen, Robbie Keane 50
Republic of Ireland team: Given, Finnan, Breen, Staunton (Cunningham 75), Harte, McAteer (Gary Kelly 84), Roy Keane, Holland, Kilbane, Robbie Keane, Niall Quinn. Iran team: Mirzapour, Mahdavikia, Golmohammadi, Peyravani, Rezaei, Kavianpour, Bagheri, Minavand, Karimi, Daei, Vahedinikbakht (Khaziravi 46). Booked: Niall Quinn (R of I), Peyravani (Iran) Referee: A Pereira da Silva (Brazil).
Independence Cup Recife, Brazil, 18 June, 1972
REP OF IRELAND 2-1 IRAN Rep of Ireland scorers: Leech, Givens Iran scorer: Parviz
The Republic of Ireland finished runners-up in the World Cup Qualifying Group 2. They collected 24 points from their ten games - trailing Portugal on goal difference. Mick McCarthy's team were unbeaten - winning seven and drawing three, scoring 23 and conceding 5.
Iran won Group 2 in the First AFC Round of World Cup qualifying. They were then runners-up in Group A of the Second Round. They picked up 10 points from 8 matches in this second group, trailing Saudi Arabia by 2 points. Iran won 4 , drew 3 and lost 1, scoring 15, conceding 10.
Iran then played United Arab Emirates over two legs in a Play Off. They won the home leg 1-0 on 25 October and 0-3 in the away leg on 31 October.