They were born only 49 days apart, though in vastly different corners of the world.

Consider the catalogues of Serena Williams and Roger Federer as a portrait of contrasting forces. Stylistically different, but in terms of sheer substance, they are two of the most decorated players of the Open Era, almost without rivals.

It feels appropriate they chose to depart from professional tennis within a span of five weeks. Williams’ retirement news arrived in a Vogue magazine essay on Aug. 9, the day after Federer turned 41. His announcement came Thursday, 11 days before her 41st birthday.

'The end of an era': WTA stars from Swiatek to Serena react to Roger Federer's retirement

“This is a bittersweet decision, because I will miss everything the tour has given me,” Federer wrote. “But at the same time, there is so much to celebrate. I consider myself one of the most fortunate people on earth. I was given a special talent to play tennis, and I did it at a level that I never imagined, for much longer than I ever thought possible.”

Williams earlier had expressed similar sentiments.

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“I’m terrible at goodbyes, the world’s worst,” she wrote. “But please know that I am more grateful for you than I can ever express in words. You have carried me to so many wins and so many trophies. I’m going to miss that version of me, that girl who played tennis.

“And I’m going to miss you.”

While parting is bittersweet -- at best -- it might be wise to adopt Williams’ mindset and see this as an inevitable evolution. Certainly, these two will be always be in and around tennis. Going forward, their love of the game will keep them engaged.

But what of the sport itself? At times like these, there are always questions about how the void will be filled. When Stefanie Graf retired in 1999, winning at Roland Garros and reaching the final at Wimbledon, coincidentally or not, that was the year Williams won her first major. When Pete Sampras walked away after the 2002 US Open, he had already lost to Federer at Wimbledon the year before -- one year before the Swiss champion would produce his first major win in the same venue.

As it turns out, just as those void questions are resurfacing, your freshly minted US Open champions might be a good place to start.

Iga Swiatek, 20, is the youngest Hologic WTA Tour player to collect three major titles since Maria Sharapova in 2008. Players such as Ons Jabeur and 18-year-old Coco Gauff have elevated themselves into mainstream sports spotlight. Currently four of the Top 10 players in the world are under 25 years old.

Carlos Alcaraz, at 19, is the youngest No.1 player in the 49 years of the Pepperstone ATP Rankings. And in case you forgot, Rafael Nadal and Novak Djokovic, the two winningest players of all time on the Grand Slam stage, walked away with three of four majors this year.

It wasn’t long ago, Williams and Federer were the faces of the game’s future.  

Williams grew up on the public courts of Compton, California; Federer was a ball boy at the tournament in his hometown of Basel, Switzerland. Their disparate environments would shape the way they played the game. Williams was in-your-face raw power and speed and blatant desire. Federer was more fluid, a sleight-of-hand artist who beat you with finesse -- and an astonishing hand-eye coordination.

She got on the Grand Slam board first, winning the 1999 US Open at the age of 17. Federer broke through at Wimbledon in 2003 and would win three of the four majors three times in four years, from 2004-07. Williams’ career was more dispersed, marked by injuries and lengthy sabbaticals. The two times she won three majors in a single season, remarkably, came in 2002 -- and 13 years later in 2015.

Federer won 16 of his 20 major titles before the age of 30; Williams managed 10 of her 23 after turning 30. Both of them were masterful on grass -- Federer won eight titles at Wimbledon, while Williams had seven. In Melbourne and New York, it was Williams with a 7-6 and 6-5 head-to-head edge, respectively. On clay, which was less conducive to their skill sets, Williams won three Roland Garros titles and Federer one.

On six occasions -- the number somehow seems low -- they won the same Grand Slam event. The first was in 2003, and the photo from Wimbledon’s Winners Ball mirrors their on-court emotions:

Williams, wearing a strappy black dress, hair pulled back, is grinning broadly. Federer, long brown hair scooped behind and well below his ears, is wearing a black tuxedo and a red bow tie -- and, with lips clenched tightly, something that approaches a grimace.

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More than 14 years later, it happened for the last time, in Australia. Williams, already pregnant with daughter Olympia, defeated sister Venus for her final major triumph, at the age of 35. Federer, hair considerably shorter, was a five-set winner in 2017 against rival Rafael Nadal. One year later, he would capture his final major in Melbourne, at the age of 36.

Even considering Federer played nearly 500 more matches, their career achievements are cut from the same cloth. Federer won 103 titles, 30 more than Serena. But Williams won more Slams and held the four major titles simultaneously twice, in 2002-03 and 2014-15. She won four Olympic gold medals, three in doubles, versus Federer’s silver and bronze in singles and a gold in doubles.

Williams’ winning percentage (858-156, .846) is slightly better than Federer’s (1,251-275, .820). Perhaps the statistic that best captures their consistent, unrelenting brilliance is the relationship with the No.1 ranking. Williams was on top for 319 weeks, nine more than Federer. Her first ascension to the throne came in 2002, the last some 15 years later. Federer’s first (2004) and last (2018) were no less impressive.

It might be some time before tennis aficionados wonder how Williams and Federer will be replaced. They came into the tennis world at the same time, dominated for close to two decades and now leave together.

It’s only fitting.