(Refiles to clarify day in second para)
By Will Swanton
NEW YORK Aug 28 (Reuters) - Walking out the door, Venus Williams vowed to be back.
The 33-year-old American lost a heartbreaker to China's Zheng Jie 6-3 2-6 7-6(5) in the second round of the U.S. Open on Wednesday before rejecting any possibility of retirement.
"Oh wow, I definitely want to come back for the atmosphere," she said. "I'll get there. I just have to keep working on it. I've had a tough set of circumstances to work through, especially this year, last year and the year before.
"I've been dealt some cards that aren't easy, but I have to play with them. I'm a fighter."
Williams suffers Sjogren's Syndrome, which causes fatigue and joint pain, and has been hampered this year by back pain.
Champion in New York in 2000 and 2001, Williams had a parochial crowd on her side as the match went down to the wire.
A rushed volley at five-all in the deciding tiebreaker proved costly.
"I should have made the shot," she said. "I rushed so badly and didn't make it. I had a lot of opportunities, I was always stepping up and putting myself in a good position ... but I just dug myself into so many holes.
"I fought as hard as I could to get out of them, but sometimes it just wasn't enough."
Williams will contest the doubles with her sister Serena.
She planned to sit back and watch the next era of American women's tennis.
"I'm happy to see them doing so well," she said. "They all seem really talented.
"I'm looking forward to them continuing to develop their games and hopefully be able to win big matches, big tournaments, and continue to influence the next generation, as well."
Former world number one Williams, who upset 12th-seeded Belgian Kirsten Flipkens in the first round, is now ranked 60 in the world, but Zheng was thrilled to fell the former champion in front of her home crowd.
"It's unbelievable I can beat her," she said in a courtside interview. Zheng next faces 18th-seeded Spaniard Carla Suarez Navarro in the third round.
(Editing by Ian Ransom)