MONACO -- L.J. van Zyl of South Africa and Lashinda Demus of the United States both set this year's world-best times in the 400-meter hurdles at the Herculis Super Grand Prix on Tuesday.
Van Zyl's late burst over the final 10 meters took him past Bershawn Jackson -- the 2005 world champion and Olympic bronze medalist last year in Beijing -- who looked to be coasting to victory.
Van Zyl won in 47.94 seconds, beating Jackson's mark of 48.03 set at the U.S. Championships last month.
Three days after breaking her own 2009 world-best time at the Crystal Palace meet, Demus improved with 53.63 -- a fraction quicker than the 53.65 she ran at the meet in London on Saturday.
Demus had also set a season's best when she ran 53.78 last month at the U.S. Championships.
Maggie Vessey of the United States also set a world-best time for 2009 in the women's 800.
Vessey even surprised herself by clocking 1 minute, 57.84 seconds to beat Russian Anna Alminova's mark of 1:57.86, set in Cheboksary, Russia, only five days earlier.
"I'm usually last, being up there with everyone is really racing," Vessey told French television after her win in warm temperatures at Stade Louis II.
Vessey's win was even more unexpected considering she ran 2:00.13 at the Golden Gala in Rome just over two weeks ago, and only 2:01.32 at the U.S. Championships last month.
Less than three weeks ahead of the world championships in Berlin, Croatian high jumper Blanca Vlasic narrowly beat Germany's Ariane Friedrich. Both passed 6 feet, 8 inches, but Vlasic did so at the second attempt, while Friedrich did so on her third try. Both then failed to pass 6-8 3/4.
Vlasic, the Olympic silver medalist in Beijing, could find it harder when she takes on Friedrich in front of her own fans at the worlds, yet seems to be relishing the challenge.
"I hope they will also have some energy to cheer for me," Vlasic said. "I'm not worried about that, I have lots of fans in Germany."
Elsewhere, Olympic champion LaShawn Merritt of the United States won the men's 400, despite a difficult start.
"I was a little bit restricted at the start," said Merritt, who was looking ahead to winning a gold medal in Berlin.
"In 2007 I came second, I don't have a world title under my belt," said Merritt, who got a silver in the 400 two years ago in Osaka, Japan. "I want that world title."
World record-holder and Olympic champion Dayron Robles of Cuba won the 110 hurdles. He knows he will need to improve before Berlin.
"All I have to do is keep working hard and things will happen," Robles said.
Elsewhere, Shelly-Ann Fraser won the women's 100 in 10.91. Debbie Ferguson-McKenzie of the Bahamas was second in her season's best of 10.97. Veronica Campbell-Brown of Jamaica was third in 11.03.
"When you get under 11 seconds it's always good," Fraser said. "I'm just happy that I came out here and won against a quality field."