In October 1927, a 26-year-old secretary named Mercedes Gleitze became the first British woman to swim across the English Channel. After being accused of cheating, Gleitze mounted a “vindication swim,” wearing a Rolex watch around her neck to demonstrate the water resistance of the brand’s new hermetically sealed Oyster case.

Although she didn’t finish, she did put the watch to the test for more than 10 hours under harsh conditions in cold seawater, and her original record was officially recognized.

At the time, mechanical watches were vulnerable to ruinous moisture and dust, so Oyster’s advancement in waterproof case construction represented a huge technical leap that paved the way for rugged sport watches in the decades to come.

Gleitze’s historic swim made headlines on both sides of the pond. She even appeared in a Rolex advertisement on the front page of the Daily Mail, testifying to the watch’s reliable and robust water resistance. With that, Rolex founder Hans Wilsdorf pioneered the concept of sports marketing via athlete brand ambassadors, or “testimonees,” as he called them.

And that was just the beginning. In 1935, Sir Malcolm Campbell wore an Oyster as he piloted the Blue Bird 5, a 28-foot-long, 2,300-horsepower supercar on the beach at Daytona, Fla., to claim the world speed record (with an average speed of 276 mph), putting Daytona on the map as a world-class motorsport capital.

Each January, drivers from International Motor Sports Association, NASCAR, IndyCar and Formula 1 compete for a Rolex Daytona watch, inscribed with “Winner” on the back, at the annual Rolex 24 At Daytona endurance race at Daytona International Speedway.

Today, the brand’s iconic gold crown is front and center on banners, scoreboards, timing clocks and television screens at high-profile sporting events around the world. Its investments spotlight tennis, golf, motor racing, equestrian sports and yachting regattas.

Rolex is particularly prominent in tennis, as the sponsor of all four Grand Slam tournaments: the Australian Open, the French Open, Wimbledon and the US Open.

Last month in Geneva, Rolex also sponsored the third annual Laver Cup tennis tournament.

The international men’s competition, which takes place in a different city each year, was the brainchild of headliner and longtime Rolex testimonee Roger Federer, the 20-time Grand Slam men’s singles champion, who named the event after his childhood hero and fellow testimonee, Rod Laver. Captaining Team Europe for its third straight victory this year was yet another tennis legend testimonee, Björn Borg, winner of 11 Grand Slam singles titles over the course of his esteemed career.

Rolex also sponsors the Davis Cup, the leading international men’s team competition, and maintains close ties with the sport’s governing bodies: the men’s Association of Tennis Professionals (ATP) and Women’s Tennis Association (WTA).

Along with superstars such as Federer, the brand’s testimonee roster includes these recognized international champs and rising stars: Juan Martín Del Potro (Argentina), Grigor Dimitrov (Bulgaria), Caroline Garcia (France), Angelique Kerber (Germany), Garbiñe Muguruza (Spain), Lucas Pouille (France), Milos Raonic (Canada), Sloane Stephens (United States), Dominic Thiem (Austria), Stefanos Tsitsipas (Greece), Jo-Wilfried Tsonga (France) and Caroline Wozniacki (Denmark).

Rolex’s golf bench is equally deep, thanks to its long legacy in the game of kings, inking its seminal partnership with Arnold Palmer in 1967. Since then, its testimonee list has grown to include luminaries such as Tom Watson, Phil Mickelson and Tiger Woods. And with a keen eye on the future of the sport, the brand has also enlisted what it calls “The New Guard,” representing the next generation of champions, including Bryson DeChambeau, Rickie Fowler, Brooks Koepka, Hideki Matsuyama, Jon Rahm, Jordan Spieth and Justin Thomas.

Like in tennis, the brand has a deep-rooted involvement with golf, providing support not only to elite and up-and-coming players, but also to the main professional tours and governing bodies, as well as the Masters, the US Open Championship, the US Women’s Open Championship and the Open, which dates back to 1860. For almost 40 years, Rolex has been a patron and official timekeeper of the prestigious event played on the United Kingdom’s finest links courses, drawing the widest international field from the four Majors.

With almost a century of sports partnerships to its credit, and a veritable dynasty of crown-jewel sporting events to burnish its signature crown logo, Rolex remains the undisputed MVP watch brand in the wide world of sports.

All at London Jewelers, 2046 Northern Blvd., Manhasset, LI