The Olympic champion David Rudisha equalled the best time in the world this year as he won the 800 metres at the Glasgow Diamond League meeting.
Rudisha, who is still recovering from a knee injury that cut short his 2013 season, returned to Britain for the first time since shattering the world record at the London Olympics and won the race in one minute 43.34 seconds.
The Kenyan was more than two seconds clear of South Africa's Andre Olivier in second and equalled the best time of the year set by his countryman Asbel Kiprop last week.
However, he was well short of his stunning 1:40.91 set at London 2012.
Olympic gold medallists Allyson Felix of the United States and Jamaica's Shelly-Ann Fraser-Pryce are also working their way back from injuries and both were run-down in the closing stages of their respective sprint races.
Fraser-Pryce was quick out the blocks in the 100m but Trinidad and Tobago's Michelle-Lee Ahye surged past her to win in 11.01 and stay undefeated this season.
The Jamaican, who was hampered by a leg injury earlier in the year, crossed the line second in a season's best time of 11.10.
Felix is working her way back to form after suffering a hamstring injury at last year's world championships and could only finish second in the women's 200m after being pipped on the line by Dafne Schippers of the Netherlands, who won in 22.34.
Queen Harrison won the women's 100m hurdles 12.58, after easing past compatriot Lolo Jones in the final 30 metres, while former world championship silver medallist Silas Kiplagat strode clear in the home straight to win the men's 1500m in 3:32.84.