Mo Farah's bid to add the World 10,000m and 5,000m titles to his Olympic golds remains on track after he eased into the final over the shorter distance.
The defending champion was fifth in his heat, the final automatic qualifying position, in 13 minutes 23.93 seconds.
If he wins Friday's final, Farah will emulate Ethiopia's Kenenisa Bekele and become the second man to win 10,000m and 5,000m Olympic and World titles.
"You have to do the job without going crazy," the Briton told BBC Sport.
"My body feels good, the team have been looking after me well and I'm recovering well."
The 30-year-old, who won the distance double at the London 2012 Olympics, became the first British man to win a 10,000m world title last Saturday.
And he began his defence of the 5,000m crown he won in Daegu in 2011 in comfortable fashion.
He was in third or fourth for much of the heat before taking the lead with three laps to go and easing off in the final 200m, once he realised his safe passage into Friday's final was secure.
Muktar Edris set the fastest time of the two heats, clocking 13 minutes 20.82 seconds.
The Ethiopian sprinted past Farah down the finishing straight but the Briton was more concerned with conserving as much energy as possible for the final in Moscow's Luzhniki Stadium.
"I just wanted to do as little work as possible to be fresh in the legs, ready for the final," said Farah, who finished behind training partner Galen Rupp of the United States.
"Galen and I looked across and, with top five qualifying, I said save as much energy as you can. I wanted to run comfortably and not sprint all out and tire myself out for the Friday."
Olympic bronze medallist Robbie Grabarz qualified for the high jump final in joint first place. He cleared 2.29m after four first-time clearances.
Jessie Williams of the United States and Aleksey Dmitrik of Russia, who won gold and silver two years ago, both failed to make Friday's final.