Kenya's David Rudisha and Botswana's Nijel Amos both claimed comfortable victories in their respective 800m heats on the first day of the World Athletics Championships.
The battle between the pair has been one of the key storylines ahead of the meeting, and neither runner was in the mood to be at the centre of a shock on Friday.
Commonwealth champion Amos, who finished second behind Rudisha at the 2012 Olympics, eased home in a time of 1:47.23 in the opening heat.
Despite finding it difficult to deliver his best form in the last couple of years, it was a typically dominant race from Rudisha as the Kenyan controlled the tempo of his heat to win in 1:48.32.
Defending champion Mohammed Aman, who won the title while both Amos and Rudisha were injured in 2013, was also comfortable on the way to winning the second heat.
It was bad news for British fans in Beijing as Michael Rimmer finished fourth in Rudisha's heat to narrowly miss out on a place in the semi-finals, while Kyle Langford could only manage a seventh-place finish in his race.
