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.
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."