Thirty-nine-year-old Regina Jacobs broke Romanian Doina Melinte's indoor world record for the women's 1,500 metres at the Boston Games on Saturday.
Jacobs, a U.S. champion 22 times at various distances, went under four minutes for the first time in her career, clocking 3:59.98 to break Melinte's world record of 4:00.27 set in East Rutherford, New Jersey in 1990.
"I've always run fast here," the American told reporters. "The crowd is amazing and it's a great track."
Romania's Elena Iagar finished second at the Reggie Lewis Track and Athletic Center on Saturday in a time of 4:09.91, with American Jenelle Deatherage third in 4:12.75.
"I had 16 weeks of the best training I've ever had. I knew it was possible but you have to get up and hope the track gods are with you," said Jacobs, who ran a world record 9:23.38 for two miles at the same track last year.
"It feels pretty amazing. The hardest part was standing there, waiting to find out if I broke it (the world record).
"In 2000, I felt like I was in the best shape of my life and I never knew if I'd get there again. I pushed and pushed and now I'm back...I'm thrilled."
Stacy Dragila broke her own American record of 4.70 metres when she cleared 4.71m in the women's pole vault.
It was a good start to the season for Dragila, who last year lost her indoor world record to Svetlana Feofanova of Russia [ Images ].
She failed in her attempts to break Feofanova's world record of 4.75m on Saturday but said she thought it had been within her grasp.
"I felt like I was close," Dragila told reporters. "I think I came off the pole too soon but today I felt very aggressive at take-off."
Maurice Greene won the 60 metres, running a time of 6.52 seconds to edge out Jon Drummond (6.56) and Tim Harden (6.57).
"I'm getting the rust out," Greene said. "I think it was a pretty good race for being my first real competition of the year.
"I kind of scared myself at the start (because he got out of the blocks so quickly), then I hesitated, so I had to pick it up in the middle.
"I was next to JD (Drummond) and he's one of the best starters in the world. I couldn't believe I got out of the blocks like that. I scared myself."