MONACO -- Usain Bolt overcame a tentative start to win the 100 meters in 9.88 seconds at the Monaco Diamond League meet Friday, beating a strong field in a tuneup for next month's world championships.
The Jamaican improved his personal best this season by 0.03 seconds but was well short of his world mark of 9.58 seconds.
Nesta Carter of Jamaica was second in 9.90 and Michael Rodgers of the U.S. was third in 9.96. They were followed by Michael Frater of Jamaica (10.01) and European champion Christophe Lemaitre of France (10.03).
Bolt got off to a poor start and battled all the way on a fast track and with a slight tail wind. The triple Olympic champion failed to beat the Herculis meet record of 9.82 after surging ahead in the last 20 meters.
"Nesta Carter, Michael Frater are very good starters, better starters than me," Bolt said. "But the last 60 (meters) are the best part of my race, so I was never really worried. Overall it was good."
Bolt, who competed for the first time on the Stade Louis II track, is unbeaten this season and said winning races, even by small margins, is the most important thing ahead of the worlds.
"For me it's always key to keep winning," he said. "And I'm getting better. My last 60 meters have improved dramatically. I need to work on my reaction time, but I've been doing great in training, so I'm just focusing and I feel ready."
The worlds start Aug. 27 in Daegu, South Korea. Bolt's last race before the championships will be the 200 at Stockholm next week.
Bolt was hampered by injuries last season. He has said that he won't lower his 100-meter world record this year and is concentrating on defending his sprint titles in Daegu.
"My aim this season is to run 9.7, maybe 9.6," he said. "For me, this year it's about building myself and go into the Olympic season fit and ready. London is the key."
In the men's 800, world record-holder David Rudisha of Kenya improved the season-best time he set last month, winning in 1 minute, 42.61 seconds.
Rudisha, who was hampered by tendinitis in his left foot earlier this season, stayed close to pacemaker Sammy Tangui in the first lap before pulling away from the pack.
Asbel Kiprop of Kenya produced a great effort in the final stretch to close the gap but had to settle for second with a personal best of 1:43.15. Nick Symmonds of the U.S. was third in 1:43.83.
"I felt great, I knew my shape was coming along nicely and it's nice to see such a fast time," Rudisha said. "Training has been going well so I was looking forward to a nice race."
Rudisha broke Wilson Kipketer's 13-year-old world record twice last year. He first ran 1:41.09 then 1:41.01 seven days later.
On an evening marked by several new world-leading performances this season, former Olympic champion Angelo Taylor resisted a late surge from fellow American Bershawn Jackson to win the 400 hurdles in 47.97 seconds.
"I'm happy with the win although it was not a great race technically," Taylor said. "But my speed and my strength are good. You know my goal for this season: I'm going for gold and only gold in South Korea."
Jackson was second in 48.22 and European champion David Greene of Britain, the Diamond League leader, third in 48.43.
Amantle Montsho of Botswana posted a fourth consecutive Diamond League win in the women's 400, with a world-leading time of 49.71. Montsho, who also won in Oslo, Lausanne and Birmingham this season, easily beat Francena McCorory and Jamaican Novlene Williams-Mills.
"This summer I'm running under 50, so it's great," Montsho said. "This was my last race before Daegu so it was important to run fast. I'm going back to Dakar to train."
Montsho's only two defeats this season came at the hands of American Allyson Felix, who finished second in the 200 meters behind Carmelita Jeter.
The United States finished 1-2-3 in that race, with Shalonda Solomon taking third place.
The three-time 200 world champion Felix got off to a good start but could not match Jeter's acceleration in the final stretch and finished in 22.32.
Felix, who has yet to decide whether she will compete in both the 200 and 400 at the worlds, said "it was not my best day today."
In the men's 5,000, Mohammed Farah posted the quickest time in the world this year and set a new British record of 12:53.11, also smashing the meet record of 13:06.36.
The race was very close and Bernard Lagat finished a stride behind Farah to improve his American record from 12:54.12 to 12:53.60.
Silas Kiplagat ran the fastest 1,500 meters this season in 3:30.47 and Renaud Lavillenie delighted his fans when he won the pole vault with a world-leading vault of 19 feet, 4¼ inches.
World champion Blanka Vlasic of Croatia won the high jump by clearing 6-5½.