Serena Williams Tightening Grasp on WTA's No. 1 Ranking Despite Age and Injury

Serena Williams' trip to a 10th semifinal appearance in Miami further solidifies her hold on the WTA Tour's No. 1 ranking.

Williams earned a trip to the semifinals with a 7-6, 1-6, 6-3 win over Sabine Lisicki at the Miami Open. It was Williams' 700th career victory. She will next face No. 2 Simona Halep, the latest player to rise and challenge the throne of the queen of tennis.

Williams is not playing her best; she's serving up more unforced errors and double faults than usual. A knee injury is apparently hampering her movement. Yet the 33-year-old will remain No. 1 next week. That will be 111 consecutive weeks, the fourth-longest streak in WTA history behind Chris Evert (113), Martina Navratilova (156) and Steffi Graf (186) . 

In fact, Williams has increased her lead over No. 2 Maria Sharapova. With extra points picked up in Indian Wells and Sharapova's early exit in Miami, Williams is in good position to hold on to the No. 1 ranking through the spring and into the summer. 

Despite obvious vulnerabilities, such as a chronic cough during the Australian Open, Williams continues to outclass the competition. Her continued reign is a testament to just how much better she is than everyone else.

Clive Brunskill/Getty Images

The season began with Sharapova having a chance to recapture the No. 1 spot at the Australian Open. She'd have to win the tournament and have Williams lose prior to the final. 

Neither happened. Instead, Williams defeated Sharapova for the 17th time. 

Last month, Williams split with long-time hitting partner Sascha Bajin, who now works with Victoria Azarenka. Some wondered if the split would impact Williams' preparation for a return to Indian Wells. Bajin was not with Williams in Australia when she won her 19th Grand Slam. 

No matter what obstacles arise, Williams finds a way to overcome. When her serve disappeared against Lisicki, Williams decided she had to "give 200 percent," as The Associated Press noted on Tennis.com. The fight harder, find-away spirit is what has made Williams one of the greatest female athletes of all time. 

Last year, in a Time magazine article on the "100 Most Influential People," Miami Heat guard Dwyane Wade wrote about what he admired most in Serena: 

"

Serena is a friend, but I also look up to her as a fellow athlete. I respect her relentless work ethic, focus, drive and discipline. I understand what it’s like to sustain injuries and the fight it takes to come back from them. I admire her ability to fight and how she has defied the odds with sheer determination and heart.

"

Williams has overcome a number of injuries and ailments in her career. The most serious was a life-threatening pulmonary embolism in 2011. 

Doubts arose about a recovery. Some wondered if she could ever return to championship-level tennis. That was six Grand Slams ago. 

Every year, tennis commentators talk about the inevitable decline that comes with age. Perhaps the increased unforced errors, double faults and nagging injuries are all signs. As with all greats, her career will some day, even if it's five years from now, come to and end. 

In the meantime, Williams continues to defy the odds and beat back the challengers.