For Djokovic it was a repeat from 2011 but it wasn't a yearlong run as Roger Federer regained the top ranking for a period after Wimbledon.
For Azarenka it marked two tours at the top spot, the first after she won the Australian Open and the other after the summer. She won her first 26 matches in 2012 and four tournaments by mid-March.
Djokovic's 2012 season only paled in comparison to 2011 when he won 10 tournaments (three majors) and went 70-6. In 2012, he repeated as the Australian Open titlist and was 75-12. He was second at Wimbledon and the U.S. Open, events he won the previous year.
Federer grabbed the limelight from Djokovic when he won Wimbledon for a record seventh time, pushing his own all-time best number of Grand Slam championships to 17 and retaking the No. 1 spot in the rankings.
That allowed him to tie -- and subsequently pass -- Pete Sampras for most weeks at No. 1 in the rankings. Federer set the groundwork for moving back to No. 1 by closing 2011 with three championships but when he couldn't match that finish Djokovic went back to No. 1. Federer, second in the year-end rankings, has held the No. 1 spot for 302 weeks.
Men's tennis Big Four divided the Grand Slam titles among themselves. Djokovic Federer, Andy Murray and Rafael Nadal occupied 12 of the 16 major tournament semifinals berths in 2012. Nadal was injured and didn't play at Wimbledon or the U.S. Open or the figure might have been higher.
Djokovic took the Australian Open, beating Nadal in the final; Nadal won the French Open (for an Open Era record seventh time), beating Djokovic in the title match; Federer topped Murray at Wimbledon; and Murray defeated Djokovic for the U.S. Open championship and his first Grand Slam title.
Murray was the winner over Federer in the gold-medal match at the Olympics.
If Federer stole some of Djokovic's thunder, women's tennis was lauding Azarenka while noting the extremely strong play of Serena Williams.
Azarenka took the Australian Open, roaring by Maria Sharapova in the final, but Sharapova completed the career Grand Slam by beating Sara Errani in the finals of the French Open. That put Sharapova back at the No. 1 spot in the rankings, a place she'd hold for four weeks until Azarenka regained it.
After Roland Garros, however, the year belonged to Williams. After a stunning first-loss at the French Open, Williams won 31 of her 32 matches and collected titles at Wimbledon, Stanford, Calif., the Olympics, the U.S. Open and the WTA Championships. She and sister Venus also won doubles titles at Wimbledon and the Olympics.
Serena Williams won seven titles and lost just four of her 62 singles matches and once in 14 doubles matches.
Former No. 1-ranked Kim Clijsters announced she was retiring after the 2012 U.S. Open. She'd stepped back from the game once before -- in May 2007 -- but returned in the summer of 2009. She won the U.S. Open that year and again in 2010. But injuries cut into her playing time and she retired after a second-round loss in the 2012 Open.
She won seven of her 41 career WTA championships after her first retirement, including the 2011 Australian Open, her fourth major tournament title.
Ferrero was No. 1 for eight weeks in 2003 after he won the French Open and was second at the U.S. Open. He won 16 ATP championships.
Roddick replaced Ferrero at No. 1 for 13 weeks. He won the 2003 U.S. Open and was a three-time finalist at Wimbledon (including a classic against Federer -- 16-14 in the fifth set -- in 2009). He won 32 titles in his career.
Federer knocked Roddick from the top spot effective Feb. 2, 2004. Since then -- just short of eight years -- only Federer, Nadal and Djokovic have been ranked No. 1 in men's tennis.
The Czech Republic pulled off a double not accomplished since 1990 when its women tennis players won the Fed Cup and the men claimed their first Davis Cup championship.
Lucie Safarova won a pair of singles matches and Petra Kvitova one in the Nov. 4 Fed Cup final as the Czech posted a 3-1 win over Serbia. Kvitova had won both her singles matches in the semifinals and quarterfinals earlier in the year.
Tomas Berdych was instrumental in getting the men's team to the finals but it was Radek Stepanek who won the final match of the best-of-five final against Spain. Berdych was 5-0 in singles and teamed with Stepanek for a 3-0 record in doubles in the three series before the final.
Berdych won his first singles match in five sets and he and Stepanek won doubles. Ferrer beat Berdych in the fourth match before Stepanek defeated Nicolas Almagro for the championship.