When she was still a teenager but already a tennis star, Venus Williams struggled to envision herself playing after 25. Now nearly a decade past that age, Williams knows better than to set an expiration date.

Playing well since Wimbledon, she felt especially youthful on the court in Monday’s U.S. Open match against Kimiko Date-Krumm, nine years Williams’s senior at 43. After an early stumble, Williams beat Date-Krumm, 2-6, 6-3, 6-3, to advance to the second round.

“According to Kimiko, I have another decade,” Williams said. “She set the prime example. She’s top 100 and no one can beat her easily. She’s breaking the mold.”

Williams seemed to overpower Date-Krumm when the match began, her serves zipping by with authority as she handily won her first service game. Date-Krumm was down 0-40 in her first service game, but then saved five break points to hold serve. She went on to get a double break for a 4-1 lead over Williams en route to a 6-2 first-set win.

Williams said Date-Krumm’s return shots were tricky at first. Date-Krumm said that younger players, Williams included, don’t like her shots because they are low and flat.

Williams is rarely the younger player in matches anymore and hasn’t been described as one in a while, but as play progressed, she started to look the part. She got out to a 4-0 lead in the second set and won, 6-3. In the third set, she was poised to win without dropping a game, up 5-0. Though she dropped the next three games, she still escaped with a win to advance .

“Definitely I was younger today,” Williams said. “But when you step out on the court, I don’t think anybody thinks about age because if you’re out on this tour, it means you deserve to be here. You’ve got the skill. It must mean you know how to play.”

It’s been six years since Williams won a Grand Slam singles title, in which time she’s balanced other commitments and interests like fashion and interior design. In 2011, she said she had Sjogren’s syndrome, an immune-system disorder that can cause stretches of fatigue.

Her recent play has been encouraging. She beat her sister, top-ranked women’s player Serena Williams, to advance to the Rogers Cup final, where Venus lost to 25-year-old Agnieszka Radwanska . Her run in the tournament put her back in the top 20, and she’s poised to finish this year ranked higher than she was at the end of 2013, when she was No. 49.

Despite playing deeper in some tournaments, Williams expects to field questions about her age and eventual retirement, but she said she doesn’t think about it. At one point in her post-match media session, a reporter bluntly asked her, “Do you feel old out there?”

“Not yet,” she said smiling.

“People have been trying to retire me since I was, like, 25,” she told reporters at Wimbledon. “For some reason in tennis, we always do that to our players. It’s weird. We don’t encourage them to stick around. It’s like, ‘Get out of here.’

“I’m not getting out of here. I think this year has been a great year for me. I’ve had some tough losses, but I’ve learned a lot from them. I’m finding my way back on my feet. I’m proud of myself for what I’m achieving on the court.”

Date-Krumm also isn’t ready to commit to retiring by a certain point. She took 12 years off when she stopped playing from 1996 to 2008, and she’s finished the year in the top 100 every year since 2009. She said she considers retirement every so often, but still feels motivated to play, so she does.

Things are different now than they were at the start of her career. Sure, she goes to the gym every day and gets her sleep, but she also enjoys a glass of red wine here and there because she wants to enjoy her life, too.

In Williams, Date-Krumm sees a woman who can physically still compete but knows firsthand that the mental exhaustion is often harder to get past.

“Sometimes, it’s mentally tough,” Date-Krumm said. “Physically, I think she’s okay, but it’s if she’s motivated. Tennis is everyday practice and practice, or it’s traveling everywhere. You only spend time at a tennis court or hotel. It’s not an easy life.”