Sanya Richards continued her quest for a second AF Golden League jackpot of US$1 million with a superb win at the Exxon Mobil Bislett Games in Oslo.

Richards and her 400 metre rivals were the first on track after torrential rain and thunder and lightning delayed the start of the meeting for over 30 minutes.

Despite the conditions, the 24-year-old American produced a magnificent performance when she stormed to victory in a world-leading time for 2009 and meet record of 49.23seconds.

Richards may not have won a major global title - although she intends to rectify that in next month's World Championships - but she has dominated the GL series having been unbeaten for almost five years.

The 2005 world silver medallist stood head and shoulders above her rivals, with Olympic champion Christine Ohuruogu finishing sixth, as they attempted to match her fast early pace before those who tried, failed to cope with her finishing speed.

Olympic runner-up Shericka Williams was the nearest in 49.98secs as Amantle Montsho behind her also clocked a season's best of 50.71.

"I did not expect a world lead after the storm and it's a pity I only equalled the meeting record," said Richards whose next outings are in Rome next Friday and Paris seven days later.

Richards added: "We were all worried what would happen and what time we would be running. I'm happy with the way I'm now running and I can fully focus on the other races."

Yelena Isinbayeva remains in the hunt for the jackpot but faced one of the biggest scares of her life although she survived to win the pole vault on countback with a height of 4.71m.

Isinbayeva, who just got the verdict on less failures ahead of Poland's Monika Pyrek, said: "It was one of the most difficult competitions of my career."

The 27-year-old Olympic champion who entered the competition just as the weather turned, added: "I was so worried and nervous of what would happen.

"There was the usual waiting for me to start and when I did, the storm came and there was more waiting. But I won and can look forward to the next competitions."

Kenenisa Bekele, winner of the 5000m in 13:04.87, Tero Pitkamaki who threw the javelin 84.63m, Kerron Stewart who triumphed with a time of 10.99 in the 100m and and Cherry Damu who took the 100m hurdles in 12.68, also remain in contention for the huge cash bonus.