Paula Radcliffe will run in tonight's 10,000metres final.
The decision was announced at 11:30am in Athens, barely 10 hours before the race which begins at 9:50pm (7:50pm BST).
Radcliffe has been mulling over whether to enter the 10,000m since her marathon disappointment on Sunday, when she withdrew from the race four miles from the finish.
She is the fastest woman in the world this year over the 10,000metres distance, by a massive 26 seconds, but there have been fears over whether Radcliffe will be too physically drawn or mentally fatigued to race again.
However her decision, which Radcliffe has waited almost until the very last moment to announce, suggests that the marathon world record holder feels confident about her chances over the shorter distance.
The 30–year–old finished fourth over 10,000m at the Sydney Olympics four years ago, having led for much of the race before being outpaced on the final lap.
She was a silver medallist at the 1999 World Championships, but again finished fourth at the 2001 edition.
Her lone 10,000m gold medal came at the European Championships of 2002.
Since the heartbreak of Sunday, when an exhausted Radcliffe pulled up at the side of the road and wept at her failure to complete the course, she has kept a largely low profile.
Aside from a television interview and press conference on Monday, during both of which she burst into tears, Radcliffe had given no hints of her plans, other than to gradually step up her training.
At her press conference, Radcliffe explained how competing in the 10,000m had hardly crossed her mind, but added that the race could offer a chance to make amends.
"I came to run and win the marathon," Radcliffe said on Monday.
"I am desperate to redeem something from all that work but I will not put myself into that arena if I am not right."
By staying in Athens, it has been apparent that Radcliffe has given serious consideration to competing.
Because she will be 34 by the time of the Beijing Games, tonight's race has been perceived as perhaps Radcliffe's best chance of an Olympic gold.