THE X Factor charity single Hero is certain to reach the number one spot tomorrow and is set to be the fastest selling of 2008.

It is outselling the rest of the Top 10 singles combined, according to latest sales reports.

The record, in aid of Help The Heroes and the Royal British Legion Poppy Appeal, is also outselling the current No 1 single by Girls Aloud , The Promise, by four to one.

All 12 finalists in this year's series, including Manchester's now eliminated Scott Bruton, recorded the cover of Mariah Carey's classic.

Tonight's ITV1 show sees the remaining nine acts taking on Disco Week, with a special guest performance by Pop Idol winner Will Young.

Atherton's Laura White, 21, has had a hard week, suffering badly from homesickness. But she is trying to stay focused on the competition and has had welcome advice from Will.

Lancashire student Diana Vickers, 17, current favourite to win, is still suffering from nerves despite the acclaim she's had from the judges.

"Every week she feels like she will be going home and can't believe her luck when she's not in the bottom two," said an X Factor spokesman.

"This week, for the first time, Diana has some sexy male dancers to work with and she's worried whether she'll be able to pull off the sexy dance moves."

Spain's Ruth Lorenzo, along with the other finalists, went to the James Bond Quantum of Solace film premiere this week.

She was shocked when Dame Judi Dench revealed she watched Ruth every week, had been voting for her and said her version of Purple Rain should be released as a single.

Daniel Evans, who survived last week's sing-off against Scott, is odds-on favourite to get the boot tonight.

Click here to read Ian Wylie's TV blog.