Olympic champion Elaine Thompson beat Dafne Schippers in the women's 100 metres as the Diamond League arrived in London, while Mo Farah delighted the home crowd in the final race.
Thompson came second to Blessing Okagbare-Ighoteguonor in her heat but defeated the Nigerian and Schippers in the final with a time of 10.94 seconds into a headwind.
Following her win, the Jamaican said: "I have done two rounds of Diamond League but this preparation is all about the World Champs in a couple of weeks.
"I have to get used to doing the two rounds because this is how I can prepare best. I am looking forward to being back in the stadium."
That race preceded Farah's participation in the 3000m - a non-Diamond League event - and he rekindled memories of his Olympic double in London.
The 34-year-old continued his preparation for the World Championships with a time of seven minutes and 35.15secs, finishing ahead of Spain's Adel Mechaal and fellow Brit Andrew Butchart.
Nijel Amos and Allyson Felix set world leading times in the men's 800m and women's 400m respectively, while Kendra Harrison outdid former Olympic gold medallist Sally Pearson in the women's 100m hurdles.
Katerina Stefanidi was unable to clear a Greek record height of 4.91m in the women's pole vault but the Rio 2016 champion still triumphed.
That was not the case for Olympic women's high jump winner Ruth Beitia, though, as she came sixth - Mariya Lasitskene clearing 2m for the win.