The four-man race includes two conservatives and two reformers
Iran has announced the details of a series of televised debates to be held in the run-up to the 12 June presidential election.
In a first for the country, each of the four candidates will go head-to-head with his rivals starting on 2 June.
The four men will also get equal air time for their individual campaign films and radio broadcasts.
The BBC correspondent in Tehran says the campaigns are looking increasingly slick and professional.
Iran's electoral council on Wednesday approved four candidates, including incumbent President Mahmoud Ahmadinejad and former Revolutionary Guards chief, Mohsen Rezai.
The two conservatives will be challenged by two leading reformists - former premier Mir-Hossein Mousavi and ex-parliament speaker Mehdi Karoubi.
The order of the debates was determined after the candidates drew lots on state television on Wednesday.
Air time: 1800-1930 GMT on IRTV3
2 June: Karoubi-Rezai
3 June: Ahmadinejad-Mousavi
4 June: Mousavi-Rezai
6 June: Ahmadinejad-Karoubi
7 June: Karoubi-Mousavi
8 June: Ahmadinejad-Rezai
Source: ISNA news agency
It is the first time Iran is holding the individual televised debates, but it is perhaps best not to call them "American-style" in the country where they still chant "Death to America", says the BBC's Jon Leyne in Tehran.
Before the last election, there was just one televised debate involving all candidates, and another before the second round involving the two front-runners.
Prior to the debates, the candidates will be given airtime on state TV for their own 45-minute campaign videos.
In the last election, a particularly powerful video for Mr Ahmadinejad boosted his image as a man of the people, and helped propel him to the presidency, so the films are crucial, our correspondent says.
Campaigning runs until 10 June, with results due a day after the 12 June vote.