Venus Williams, nagged by lower-back woes and with only one win since early April, ousted 12th seed Kirsten Flipkens on Monday to reach the second round of the US Open.
The 33-year-old American, the oldest player remaining in the women's field, dispatched the Wimbledon semi-finalist 6-1, 6-2 in just 84 minutes, avenging a loss to the Belgian earlier this month at Toronto.
Williams, now 15-0 in US Open first-round matches, advanced to a second-round date with China's Zheng Jie at the year's final Grand Slam event after missing Wimbledon with lower back pain and making a first-round exit at the French Open.
"I stay positive because I know I can play some great tennis," Williams said. "Sometimes you just have to go through more than what you want. Sometimes you have to have losses. It always motivates me a lot to do better and work harder."
Seven-time Grand Slam champion Williams, who has slid to 60th in the rankings, has not made it past the fourth round of a major event since reaching the 2010 US Open semi-finals.
"I haven't had a lot of chances to play healthy this year, have had injuries and what have you, so I'm just going to have to keep working my way into it maybe more than some of the other players," Williams said. "But I know I can do that."
Losing to Flipkens three weeks ago inspired Williams, in her 60th major tournament, to emphasize improving her serve in US Open training.
"I started out really strong in Toronto and didn't end up as well as I like," said Williams, who sported bright purple hair.
"She's playing very well this year. She's confident. You're a little impatient sometimes. You can overhit a little bit with her.
"But my serve was a lot better. Just coming back I've had to do a lot of work on my serve. I think that made a huge difference."
Williams, who suffering with a fatigue-causing disease called Sjogren's syndrome, has adopted a vegan diet to fight the disorder's effects, although she confessed some lapses in dietary discipline.
"I used to love steak, so I do miss that," Williams said. "I'm a chea-gan -- I cheat a lot. You see a picture of me eating the wrong thing -- that's why I have already confessed."
Williams, who could face world number one and younger sister Serena Williams in the US Open quarter-finals, said that the best advice she has received in her career came from Serena, though she would not say what it was.
"She has definitely given me some great advice that I still think of to this day," Williams said.