These are, of course, no ordinary athletesâ€”not your average tennis professionals. They both hold more singles Grand Slam titles than any other active player, and both are ambitious for more.
Federer reached the final of the French Open, the semis of the Australian and the US Open and the quarters of Wimbledon.
Williams reached the final of this yearâ€™s US Open after a yearâ€™s absence with injury and illness. During the six months she played in 2010, she won two Slams and reached the quarters of the third.
Yet Federer and Williams are not unique in performing at the highest of levels during their 30th year and beyond.
The womenâ€™s tour in particular has been invigorated by a lively interweaving of a new generation of faces with many established ones.
In the top 30 alone, there are twice as many women older than 28 than there are women born in the 1990s.
For every 21-year-old Petra Kvitovaâ€”who won the first tournament of the year in Brisbaneâ€”there has been a 31-year-old Greta Arn, who beat Maria Sharapova, Julia Goerges and Yanina Wickmayer, all in straight sets, to win in Auckland.
The 24-year-old Jarmila Gajdosova, who won her second career title in Hobart, was sandwiched between Na Li, 29, winning her first Premier event in Sydney, and Kim Clijstersâ€”28 and back after two years away in the new role of motherâ€”winning her first Australian Open.
The young Kvitova went on to win in Paris, Madrid and Wimbledon. The world No1, Caroline Wozniackiâ€”just 21 but top of the rankings for a yearâ€”won six titles. The 22-year-old No3, Victoria Azarenka, took two. Tall, elegant and beautiful women newly into their 20s also made inroads: Goerges in Stuttgart, Polona Hercog in Bastad, Magdalena Rybarikova in Memphis, Ksenia Pervak in Tashkent.
But scattered through these achievements are wins from women born almost a decade earlier. Thirty-year-old Lourdes Domingues Lino won her second title in four years in Bogota.
Alberta Brianti, now 31, took Fes, her first title in 11 years as a pro. Roberta Vinca, approaching 29, won three titles and reached her highest ever rankingâ€”18â€”this month. Two Spaniards who turn 30 next year, Anabel Medina Garrigues and Marie Jose Martinez Sanchez, won two titles apiece.
One match this year encapsulated the meeting of the generations: Pavlyuchenkova and Francesca Schiavone in the fourth round of the US Openâ€”the youngest versus the oldest left in the draw.
Schiavone has a knack of taking the hard road through every tournament. Few will forget her four-and-three-quarter-hour battle in the longest ever Grand Slam womenâ€™s match against Svetlana Kuznetsova in Australia this year. She went on to have Wozniacki at a set down in the quarters but lost it in three.
She lost in three-setters in Dubai, Kuala Lumpur, Cincinnati and Wimbledonâ€”in the last of them, it was 11-9 in the third. And the US Open provided more of the same.
In the third round, she lost the first set, took the second in a tiebreak and finally won in three hours, but in the next match, she faced the fast-improving Pavlyuchenkova. Again, the never-say-die Italian won the first set only to lose the next two.
This was Schiavoneâ€™s 12th US Open and her 45th consecutive Grand Slam appearanceâ€”the longest active female streak in the Open era. Yet it was not until she won her first Slam in Paris last year that she earned the WTAâ€™s Most Improved Player award: at 30.
Schiavone has had company from her compatriots, too. The 29-year-old Flavia Pennetta won her first Grand Slam doubles title in Australia this year having won seven other doubles titles in 2010, all with Gisela Dulko. She also broke into the singles top 10, and this group of Italians leads the Fed Cup rankings by a mile.
Schiavone was one half of the French Open final again this year, though there were few who expected either her or the equally popular Li to be the last women standing in Paris.
Neither had set the preceding few months alight but both proved they were two of the best movers and toughest fighters on the tour. Whatâ€™s more, their big personalities and charismatic tennis captured the pubic imagination.
Schiavoneâ€™s game combines old-fashioned tactics, varied spin, intelligent shot selection and the serve-and-volley, and she brings the kind of passion and joy to her tennis that lifts the dullest of days.
Li won over media and fans during her great run at the Australian Open. Her on-court interviews became a not-to-be-missed treat of wit, openness and free-spiritedness. She also has an attacking playing style that takes the ball early, flat and hard with clinical chess-like movement.
Between them, Li and Schiavone took out seven seeds in Paris, including several of the favourites: Sharapova, Pavlyuchenkova, Kvitova, Azarenka and Jelena Jankovic amongst them. Eventually, it was Liâ€™s day and, in winning, she emulated her opponent. In 2010, Schiavone was the first Italian woman to win a Grand Slam: in 2011, Li became the first Asian winner.
Much has been made of the mature years of the finalists but neither was fazed. From Schiavone: â€œThe years can help a lot…itâ€™s like wine: if it stays in the bottle more itâ€™s much, much better.â€
Li put it more bluntly: â€œSome people say Iâ€™m getting oldâ€”so the old woman had the dream come true.â€
However, the combined age of this finalâ€”59â€”had nothing on a match that thrilled the Wimbledon audience a month later.
Venus Williams has reached eight Wimbledon finalsâ€”five of them yielding in titlesâ€”and has won the US Open twice. Add in 12 Grand Slam doubles titles and she stands apart as one of the greats of the womenâ€™s game.
She came into Wimbledon, aged 31, having played just five matches in 2011, but stormed through her opening match for the loss of just four games. Her next opponent was just as remarkable.
Kimiko Date-Krumm played her first Wimbledon in 1989â€”before 36 of the players in 2011 women’s draw were born. She reached the semi-finals in 1996, losing in a close three-setter to Steffi Graf, and promptly retired from tennis having reached No4 in the world.
During her 12-year break, she worked for the Japanese equivalent of UNESCO and helped fund the building of a school in Laos. She also found time to run the London Marathon in under three and a half hours.
By reaching the second round, she became the oldest winner of a Wimbledon match bar one: Martina Navratilova.
With a combined age of more than 70, Williams and Date-Krumm provided the only action on a rain-soaked afternoonâ€”and it blew the Centre-Court crowd away.
They fought it out for three hours, through three sets and almost 100 outright winners, until Williams sealed the match, 8-6. It was arguably the high spot of the year for both.
Williams did not play again until the US Open where she pulled out after one match with a diagnosis of the autoimmune disease, Sjogrenâ€™s syndrome.
Date-Krumm continues to compete despite a succession of niggling injuries. She was 41 this week, two days after Williamsâ€™s younger sister, Serena, turned 30.
And so to the most successful active woman in tennis, the sixth most successful of all time.
Serena Williamsâ€™s 2011 US Open may, unfortunately, be remembered for things other than her tennis: Her outburst against the chair umpire in the final against Sam Stosur has been recorded for posterity. That would be a pity, though, for the Williams story of year-long injury and illness is an extraordinary one.
When she returned to the grass this summer after her 12-month absence, she looked as fit and strong as she had in winning her previous 13 Slams. With back-to-back wins in Stanford and Toronto, she immediately became the favourite for New York, but her lowly seeding of 28 made her route a difficult one.
Nevertheless, she progressed with ease, pausing for one tiebreak against No4 seed Azarenka before taking out No16 Ana Ivanovic, No17 Pavlyuchenkova and top seed Wozniackiâ€”all without dropping a set.
Few expected Stosur to fare any betterâ€”except Stosur, whose confident and powerful hitting prevented Williams from asserting her usual rhythm and dominance. And when Williams lost her cool at the start of the second setâ€”having lost the firstâ€”the rest was history. Stosur became the yearâ€™s third first-time Slam winner after 12 years on the pro circuit. The quiet Australian is, it seems, only just hitting her stride.
Williams will also return, probably with even greater determination, to win more titles. If she can record a 22-3 win-loss run that takes in two titles after such physical turmoil, what can she serve up when 2012 gets under way?
Well there is still one title missing from her CV that will certainly focus her steely will: the hope of Olympic singles gold.
So the story of the 30-year-olds comes back to its start, for Federerâ€™s prime motivation will surely be the same. He, like Williams, has won doubles gold, but he, like Williams, will have few more chances to turn that gold single.
MORE: The latest football news
MORE: The latest tennis news