Britain's Mo Farah will attempt to make history in Friday's 5,000m final at the World Championships in Moscow.
Victory over the shorter distance will see the 30-year-old emulate Ethiopia's Kenenisa Bekele and become the second man to hold 10,000m and 5,000m Olympic and World titles simultaneously.
Farah won both titles at the London 2012 Olympics and his 5,000m final will be live across the BBC at 17:45 BST.

Mo Farah's major medals

  • 2013 World Championship gold (10,000m)
  • 2012 Olympic gold (10,000m & 5,000m)
  • 2012 European gold (5,000m)
  • 2011 World Championship gold (5,000m) andsilver (10,000m)
  • 2011 European Indoor gold (3,000m)
  • 2010 European gold (10,000m & 5,000m)
  • 2009 European Indoor gold (3,000m)
  • 2006 European silver (5,000m)
He has been in supreme form since last summer's Games, even impressing over the shorter 1,500m distance earlier this year.
He broke the European 1,500m record at a meeting in Monaco in June, clocking three minutes 28.81 seconds to become the sixth-fastest man over the distance and taking Steve Cram's 28-year-old British record.
The Briton followed that up with victory in the 3,000m at the London Anniversary Games at the Olympic Stadium before winning his first 10,000m world title last Saturday.
However, Farah, who qualified for the final by finishing fifth in his heat, is just one of two in the 12-man final competing over both distances in Moscow - his American training partner Galen Rupp is the other.
UK Athletics head of science Barry Fudge believes it will be a "long shot" if Farah successfully defends the title he won two years ago in Daegu.
"If Mo wins a medal on Friday night he's going against the odds basically," said Fudge. "It is a long shot. [When you double up] you don't really know what's going to happen, how his body's going to respond.
"Most people wouldn't do it. Most people can't. It's hard. People just see him turn up in a stadium and run the race and go, 'Wow, that's incredible'.
"But what actually goes in to getting you to that point is a massive, massive achievement."
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Mo Farah wins 10,000m
World Athletics 2013: The moment Mo Farah won 10,000m gold.