Tennis veteran Stan Wawrinka proved age is just a number in a breathtaking opening match of his farewell tour at the United Cup, battling back from an early deficit to defeat French player Arthur Rinderknech in a grueling three-set thriller.

The 40-year-old three-time Grand Slam champion showed remarkable resilience, overcoming a significant ranking gap - from 157th to his opponent's 29th - in a match that stretched over three intense hours.

Wawrinka, who announced his retirement from the ATP tour in December, demonstrated the same fighting spirit that made him a fan favorite throughout his illustrious career. The Swiss star defeated Rinderknech 5-7, 7-6 (5), 7-6 (5) in a nail-biting contest that showcased his enduring skill and competitive spirit.

Before the match, Wawrinka expressed hope of improving his current ranking and breaking back into the top 100 before hanging up his racket. This goal reflects his unwavering commitment to excellence, remembering the days when he reached a career-high ranking of No. 3 after winning the Australian Open in 2014.

'I'm happy with the decision to retire and feeling at peace with that,' Wawrinka shared, revealing a sense of calm and acceptance about his impending departure from professional tennis. His teammate Belinda Bencic further boosted the Swiss team's morale with her own convincing 6-2, 6-4 victory over France's Leolia Jeanjean.

The United Cup, taking place in the lead-up to the Australian Open - which begins January 18th in Melbourne - provides a fitting stage for Wawrinka's farewell tour. As fans and fellow players watch this remarkable athlete's final competitive season, his determination and passion continue to inspire tennis enthusiasts worldwide.

With each match, Wawrinka is writing the final chapters of a career marked by extraordinary comebacks, memorable victories, and an indomitable spirit that transcends mere athletic achievement.