Gareth and Will will battle it out in Saturday's final
The Pop Idol result at 2100 hit BBC One's wartime drama Night Flight, which won just 4.1m viewers - one million down on the same slot the previous week.
Pop Idol viewers cast 5.8 million votes to see Gareth Gates and William Young through to the final.
The pair will be campaigning for the public's support with election-style manifestos and battlebuses in the TV talent show's final week.
Next Saturday's show will see either Gareth or Will - depending on the public vote - crowned winner and handed a record contract.
The pair will use their battlebuses to meet fans and the press to see how they would cope with fame, and have written their tongue-in-cheek manifestos of reasons why the public should vote for them.
'Celebrity strops'
Gareth, the 17-year-old bookmakers' favourite, has promised "not to become a celebrity bighead and keep my feet firmly on the floor".
He also said he would "not throw celebrity strops or become a high maintenance pop star" and would "to work hard and give my fans everything they deserve for giving me this opportunity".
Will, 23, was only 0.5% behind Gareth in Saturday's public vote and promised to "stay well clear of typical celebrity hangouts".
He also said he would "not throw celebrity strops at stalker journalists and the paparazzi (I reserve the right to break this pledge)".
Bookmakers have shortened Will's odds to win to 7-4, but Gareth is still odds on-favourite at 2-5.
Gareth won 39.8% of the votes on Saturday - with Will on 39.3% and Darius on 20.9%.
'Incredible'
Darius, who first made his name on the Popstars show, said he was not upset at being voted out and would continue his quest for stardom.
"I'm not only the luckiest boy in Britain, but the happiest," he said. "Everything that has happened to me has been incredible.
"I didn't see getting voted off Popstars as being rejection, and I don't see this year on Pop Idol as being rejection. I see it as being a great personal success.
"When I heard the result last night I was totally over the moon. I can't tell you why, but it just felt right. It was a great feeling and I also felt a sense of relief."
Concerts
He added that he would not be turning up at the auditions to become the new member of Hear'Say.
Two new concerts featuring the 10 Pop Idol finalists have been announced after 18,000 tickets for an initial two performances sold out in just two hours.
The finalists will all perform at Wembley Arena on 14 and 15 March, with the new performances announced for 16 March.
Tickets for those shows were due to go on sale on Monday.