Former whitewater kayaking world champion Rebecca Giddens used a clean first run through the first Olympic saltwater course to advance to the single kayak semifinals.

"For the most part, I paddled well, but I have some things to go home and think about to get ready for tomorrow," said Giddens, who picked up a couple of two-second penalties on her second run for hitting gates. "This year, I didn't focus on World Cups. My main focus was to come here and compete in the Games and be prepared for this."

Giddens now moves into a 15-boat semifinal field today, with the top 10 boats getting into the finals later that day.

Jennifer Bongardt of Germany was the leader on first day. Two-time defending gold medalist Stepanka Hilgertova of the Czech Republic finished in 11th place. Giddens raced in the 2000 Games, but finished out of the medals. She was the world champion in 2002.

The man-made rapid at the Helliniko Complex has been praised for the biggest, fastest whitewater of any Olympic course, and it was rough on American single canoe racer Chris Ennis. He flipped and missed a gate, a 50-second penalty, knocking him out of contention.

"I started out great and was paddling as well as I ever have," Ennis said. "I chose a bad line coming out of Gate 14, and I suffered for it."

Michal Martikan of Slovakia, who won gold in 1996 and silver in 2000, finished the preliminary round in first place.

Rebecca Giddens speeds down the slalom course during a single heat.