It was definitely a whirlwind year in the tennis world. Here are our top on-court stories of 2016.

1. French feat for Djokovic

Novak Djokovic's long-sought victory at the French Open was worth the wait. He completed the career Slam and became the first man since Rod Laver to hold all four major titles at the same time. The ovation he received was also a special moment for the Serb, who has not often had the crowd with him in the biggest matches of his career. It was perhaps natural that such a big win would be followed by something of a letdown; he won only one more title the rest of the season.

2. Serena's wins 22nd at 34

Serena Williams' victory at Wimbledon gave her Grand Slam No. 22, tied for second overall and first in the Open era. It was her only Slam win of the season, but the one-time teenage champion still pulled off a major title at 34, and that might be as notable as her total.

Serena Williams' championship at Wimbledon was one of just two tournament wins for her in 2016. Adam Pretty/Getty Images

3. Federer and Nadal struggle with health

The two biggest names in the game played only intermittently, with some impact on interest and tournament attendance. Having rarely been injured in his career, Roger Federer wasn't fully fit this season and struggled in tournaments. He had knee surgery following the Australian Open, withdrew from Miami with a stomach illness, picked up a back problem during the clay season and didn't play in the French Open, breaking his record of playing in 65 consecutive Slams. When he returned for the grass-court season, Federer's knee was still not 100 percent. He slipped and fell during his semifinal against Milos Raonic at Wimbledon, then decided to sit out the rest of the year.

Rafael Nadal is used to injury interruptions, but this season was especially painful for him. Having started shakily, the Spaniard briefly returned to form before he injured his left wrist and withdrew during the French Open, an event he has won nine times. He returned in time for the Olympics, but up-and-down play prevented him from playing after the Shanghai Masters.

4. Murray reaches the top

Often seen as the fourth member of the Big Four, Andy Murray finally got to be No. 1. In a way, it was about time, but it didn't come easily. Murray left the French Open more than 8,000 points behind Djokovic and managed to make up that gap before the season even finished. He did it with a second half that was as dominant as Djokovic's first, winning every event he played except Cincinnati and the US Open. Murray's ascent was popular and particularly special following his brother's rise to No. 1 in doubles just a few months prior. Both also finished the season as No. 1s. Andy would clinch the final top spot by defeating Djokovic to win the ATP Tour Finals, and Jamie Murray secured his position as part of the top-ranked doubles team the same week.

5. Kerber becomes new WTA leader

Compared to how long Andy Murray knocked at the door before breaking through, Angelique Kerber's rise to No. 1 happened rather rapidly. But the two do have a few things in common. Both built their games on stellar defense and reached the top by adding to their offense. They are also among the oldest players to reach No. 1 for the first time. Unlike Murray, though, Kerber had never advanced further than a semifinal at a Grand Slam or big WTA event before this season. Now, she has two Grand Slam titles and another final, and the rest of the field is chasing her.

Angelique Kerber started the season ranked No. 10 and ended it at No. 1. Timothy A. Clary/AFP/Getty Images

6. Won and done for Wawrinka, Muguruza

Stan Wawrinka and Garbine Muguruza were both conspicuous for what they did and didn't achieve. Both won a major -- Wawrinka his third at the US Open, Muguruza her first at the French Open. Both did little else at that level of significance. Wawrinka had only one other top-10 win all season, though he did win three smaller titles and reach the French Open semifinals. Muguruza reached only two other semifinals in all her other tournaments.

7. Del Potro and Argentine tennis

The second half of the season would have been a lot less exciting if not for Juan Martin del Potro. He took on the big names singlehandedly -- almost literally, given his left wrist problems -- defeating Wawrinka, Djokovic, Nadal and Murray during one four-tournament run. That included wins against Djokovic and Nadal at the Olympics, in which he was cheered on by the South American crowds. Del Potro then led Argentina to its first Davis Cup, winning a couple of five-setters in the semifinals and final. Now that's a comeback.

8. Cinderella stories

Underdogs had their days, creating a sensation by defying the odds. Shuai Zhang entered Australian Open qualifying thinking about hanging up her rackets, but she advanced all the way to the quarterfinals, shelved her retirement plans and finished the season ranked in the top 25. At the French Open, Shelby Rogers only got into the draw when another player withdrew, but she defeated three seeds to reach the quarterfinals. Kiki Bertens, meanwhile, who qualified and won at a small WTA in Germany a week before, defeated four seeds, including Kerber, to reach the French Open semifinals. Then there was Marcus Willis at Wimbledon. He is a part-time teaching pro who was the final player to get into prequalifying. He not only got through qualifying, but won his first-round match to earn the chance to face Federer on Centre Court. Willis was among three teaching pros who qualified for Wimbledon, while two amateurs reached the third round of the US Open.

Qualifier Marcus Willis waves to the appreciative crowd after his second-round loss to Roger Federer on Centre Court at Wimbledon. Julian Finney/Getty Images

It doesn't stop with the Grand Slams. In Miami, Horacio Zeballos got into the draw when Federer withdrew, defeated del Potro in the second round and lasted until the round of 16, all while his wife was on the verge of delivering their first child. Nadal's second-round opponent in Miami, Damir Dzumhur, almost quit in the heat but then saw Nadal retire instead. Monica Puig was a surprise winner at the Olympics, earning the first gold medal in Puerto Rico's history. And then there was Svetlana Kuznetsova, who played four weeks in a row to qualify for the WTA Finals. She arrived there the day the tournament began and even cut off a chunk of her ponytail in the middle of her opening win.

9. Age is just a number

While younger names kept inching up, the veterans weren't getting left behind. Led by Federer, there are nine ATP players who are 34 and older in the top 100. Some are even moving up at this age. Stephane Robert broke into the top 100 at the age of 36, while 34-year-old Paolo Lorenzi became the oldest first-time winner on the ATP Tour. Ivo Karlovic won two titles and is back in the top 20 at the age of 37, while 34-year-old Nicolas Mahut is back in the top 40. On the WTA, 34-year-old Roberta Vinci and 36-year-old Venus Williams have both kept their top-20 positions.

10. Revolving doors in doubles

With Bob and Mike Bryan dropping from their traditional position atop the doubles rankings, the No. 1 spot of men's doubles was a revolving door. Jamie Murray, Bruno Soares, Nicolas Mahut, Pierre-Hugues Herbert and Marcelo Melo were each No. 1 in either the team or individual doubles rankings at some point. Among the women, the top team of Sania Mirza and Martina Hingis split up in August. Mirza hung on for her second consecutive year-end No. 1 in the individual doubles rankings, while the French team of Caroline Garcia and Kristina Mladenovic took ITF World Champion honors.