Serena completes the comeback to beat Li Na 63 76(5) with a fantastic passing winner. Will have to see how her leg is.— Beyond The Baseline (@SI_BTBaseline) March 26, 2013
Williams played a sloppy match and fell behind 5-2 in the second set, but she rallied to win in a second-set tiebreaker to take the match in straight sets, 6-3, 7-6 (7-5). Williams' early struggles were highlighted by six double faults.
The current women's world No. 1, Williams is the top overall seed in the women's draw, and has dropped just one set in four match wins in Miami this March.
Williams has won the Miami Masters event five times over the course of her decorated career, but not since 2008, when she defeated Jelena Jankovic in the final.
The 31-year-old tennis superstar has just one singles title in 2013, winning the WTA Brisbane International in lead-up to the 2013 Australian Open last January, but she does boast an impressive 16-2 singles recording through the first three months of the season.
She has won two of the last three Grand Slam tournaments on the women's side (15 singles majors overall), and will look to inch closer to Chris Evert and Martina Navratilova on the all-time Slam list by winning her second career French Open title this June.
At this tournament a year ago, Williams lost in the quarterfinals to Caroline Wozniacki. Now she will take on the winner of Agnieszka Radwanska (4) versus Kirsten Flipkens (30) in the semifinals on Thursday.
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