Olympic champion Sammy Wanjiru has been forced to pull out of the London Marathon with a knee problem.
But his fellow Kenyan and three-time winner Martin Lel has been added to the field for the race on Sunday 17 April.
Wanjiru won in London in 2009, but dropped out at the halfway stage last year through injury.
The 24-year-old has not raced since winning the Chicago Marathon last October.
He said: "I am bitterly disappointed not to be able to race in London this year. Winning the London Marathon in 2009 was one of the great achievements of my career and I was hoping to become the champion again.
"But I have been suffering some problems with my right knee recently which meant I had to withdraw from the Lisbon half-marathon.
"Unfortunately, it has not responded well enough for me to make my final preparations for London."
Lel won in London in 2005, 2007 and 2008 and, after two years of injury problems, believes he is in shape to challenge for a fourth title.
Race director David Bedford said: "Of course we are very sad to lose the Olympic champion from our line-up as Sammy was a great champion here two years ago. We wish him a speedy recovery from his injury problems.
"But we are also delighted to announce the late addition of Martin Lel, one of the great champions in London Marathon history.
"Martin tells me his training has been going really well and he feels in shape to be able to take on the London challenge again. He is a very welcome addition to what is already a great field."