BEIJING (AP) Rarely has Mo Farah been challenged like he was Saturday.
The combined might of the Kenyan team was working to sap his strength and a stumble in the chaos of lapping runners on the last go-round made this year's 10,000-meter race at the world championships truly memorable.
It almost put a summer of doping allegations hitting his coach and training partner into the back of his mind.
Yet again on Saturday, there was no denying Farah, who is halfway home to a third long-distance double in as many major championships.
''To back it up year after year, it hasn't been easy,'' the British runner said, reflecting on a 5,000-10,000 double at the 2012 London Olympics and the 2013 worlds.
To put it in perspective, Mo Farah pretty much is to long-distance running what Usain Bolt is to the sprints. And his rival competitors, getting more desperate by the year, are trying new ploys to undo the champion.
On Saturday at the Bird's Nest, the three Kenyans in his race set a tough pace in the sweltering heat and ran as a team to wear Farah down.
''As a country, I take my hat off to them,'' Farah said. ''Some of them sacrificed medals.''
Even if they failed to break down Farah's resolve, Kenya did earn two medals - silver for Geoffrey Kipsang Kamworor and bronze for Paul Tanui.
''We worked as a team trying to beat Mo Farah,'' said Kamworor, who is the half marathon and cross-country world champion. ''But he is a tough guy to beat.''
After Farah surged into the lead, he had one more challenge to deal with. With about 350 meters to go, he stumbled, upsetting his rhythm during a vital part of his sprint finish.
''I was thinking, `Not 24 laps into it, last lap,''' Farah said.
Yet again, he regained his composure within seconds and even though the Kenyans closed in because of it, they never got past him. Farah had time to celebrate as he crossed the line with his arms outstretched and mouth wide open.
He said he was so focused on Saturday's title that the doping scandal hardly hampered his preparations.
Farah and training partner Galen Rupp, the 2012 Olympic silver medalist, are both coached by Alberto Salazar, who is under investigation by the U.S. Anti-Doping Agency for allegedly encouraging Rupp and other runners to skirt anti-doping rules.
''Obviously, when it kicked off, it wasn't easy. I just had to go home and deal with it,'' said Farah, who won his first major double at his home Olympics. ''I'm never going to have as much pressure as I had in London.''
He still has the 5,000 to run in Beijing, with a triple of global doubles beckoning.
''It is possible,'' the 32-year-old Farah said. ''It all depends on how the race happens.''
Raf Casert can be followed on Twitter at http://www.twitter.com/rcasert