Great Britain's Mo Farah finished third in his 5,000m heat to
automatically qualify for the final and stay in contention for double
Olympic gold.
Farah
won 10,000m gold on Saturday
and was given a huge roar from the crowd when introduced at the start line.
"Mo had to work hard. Even for Olympic champions
12-and-a-half laps can still be hard work. I think Mo is going to have
to be absolutely at his best to win gold. When he gets to the final
he'll want to be controlling it rather than reacting to it."
He had to work to book a spot in a second final and said: "It was pretty difficult as I was tired."
Fellow Briton Nick McCormick was 12th in the second heat and failed to reach Saturday's final.
Farah stuck around after his third place to watch the second heat to study his rivals as he bids to add an Olympic gold to his World crown in the 5,000m.
"The heat took a bit more out of me than I was expecting," added Farah. "But I'm really happy with where I am now and I've got a couple of days off.
"I kept getting caught as there was a lot of pushing and shoving going on. That's what happens in the heats and, hopefully, it will settle down in the final."
McCormick ran in the faster heat and narrowly missed out on a final spot as a fastest loser.
"I did everything I possibly could," he said. "I'm disappointed I missed out by two spots but it was a brilliant occasion.
"I loved the crowd, they were absolutely fantastic. I gave it everything but I have come a long way from where I was two years ago and I'm just disappointed not to make the final.
"I think I could have done. It was a very scrappy race. I just didn't have enough but I gave it everything, I've got no regrets."
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