EUGENE, Ore. — There are no sure things in the wacky world of pole vault. Even so, it's not bad being Brad Walker right now.

The defending world champion broke an eight-year-old American record today at the Prefontaine Classic, clearing 19 feet, 9 1/4 inches on the same field where he'll try to make his first U.S. Olympic team in only three weeks.

"The track's good, we'll say that," Walker said. "Eugene, when the weather's nice, is probably one of the best places to jump. The American record's here for me now. I know that it's a great place to jump. I know I'm confident that I can jump high here, so it just adds to my confidence for the trials."

Walker broke the record held by Jeff Hartwig at 19-9€. Then, Walker took two shots — skipping the first attempt to catch his breath — at Sergei Bubka's world record of 20-1fl, but didn't come close.

Still, it was hard to label this day anything but a triumph for the 26-year-old, two-time U.S. outdoor champion — and it was made even better because one of the guys he beat was Hartwig himself.

"I always thought if I did it, I'd want to do it at a meet that Jeff was at," Walker said. "We're great friends. We've talked a lot over the years. He's given me pointers. He hugged me and told me `Good job."'

Walker shared the spotlight at America's biggest track meet with Maria Mutola, the middle-distance star from Mozambique, who won the 800 meters for the 16th straight year in this, her final appearance at Prefontaine.

She kissed the track after the race.

"All the emotion, the stress is behind me now that I was able to finish good," she said.

The world's best-known star, Liu Xiang of China, lined up for the 110-meter hurdles, but flinched early and was disqualified for a false start, turning his trip to America into a nonevent. He scratched from last weekend's meet in New York with a sore hamstring and was apparently well enough to run Sunday, but didn't get his chance.

Asked what happened, he said "nothing happened."

"I didn't even realize I had the false start," Liu said.