Australia's red-hot Olympic favourite Sally Pearson suffered her first defeat of the season in the 100 metres hurdles as Games medal hopefuls found the going tough at a cold and wet London Grand Prix.
World champion Pearson, winner of 15 of her 16 races last year and unbeaten in 2012, led until the final two hurdles before she was overhauled by Kellie Wells of the United States who won in a time of 12.57 seconds. Pearson was two hundredths of a second behind.
Pearson won gold for Australia in the 2011 world championship in Daegu, South Korea, in 12.28 seconds the fourth fast time in history.
France's Christophe Lemaitre showed why he is rated for the Olympic 200 metres title by crossing the line in a season's personal best time of 19.91 seconds, four tenths faster than Martina Churandy of the Netherlands.
Lemaitre holds the French record of 19.80 seconds for the 200 metres hopes to go faster in the 2012 London Olympics where he is also expected to face Usain Bolton in the 100 metres race.
Kenyan Silas Kiplagat burst to the front off the final bend to win the men's mile in 3:52.44 after the race had been subject to two false starts, which were put down to a technical problem.
Romenia's Ancuta Bobocel also achieved a season personal best time of nine minutes 27.24 second in the women's 3000 metres steeplechase. The 24 year-old competed at the 2008 Olympics and won the European under-23 steeplechase title in 2009.
In damp conditions, defending Olympic champion Christine Ohuguoru won the women's 400 metres with a season personal best time of 50.42 seconds, 14 tenths faster than second place Amantle Monstsho from Botswana.
Women's javelin world record holder and Olympic champion Barbora Spotakova of the Czech Republic came off second best to Britain's Goldie Sayers who won the event with a national record of 66.17 metres.
There was a shock in the women's 100 metres with Nigerian Blessing Okagbare winning the race in 11.01 seconds, 0.02 ahead of world champion Carmelita Jeter of the United States.
Chris Taylor of the United States delivered the winning leap of 17.41 metres in the men's triple jump, well ahead of second place Leevan Sands of Bahamas.