In January, Williams took her first of three singles titles of the year by defeating Safina 6-0, 6-3 in the final of the Australian Open. In July at Wimbledon, Williams stopped Venus Williams in the championship final 7-6(7-3), 6-2.
In the Doha final, Serena Williams took the first set 6-2 behind punishing groundstrokes while her sister appeared
a step slower perhaps due to several three set matches she'd played earlier in the week. Venus Williams also appeared to struggle with a
heavily wrapped knee which had also troubled her throughout 2009.
But serving better and hitting harder, Venus Williams took leads of 4-3, 5-4 and 6-5 in the second set before her younger sister would hold serve to force the decisive tiebreaker.
Serena Williams took a 5-1 tiebreak lead before finishing the match in tiebreaker 7-4.
Williams first became the world number one in July of 2002 but saw her ranking fall to number 140 in July of 2006 following sporadic results after a 2003 knee surgery to repair a knee tendon tear.
During the period of time from the 2002 French Open until the 2003 Australian Open, Williams did not lose a singles grand slam and is the last tennis player male of female to hold all four grand slam titles at once.
Ten years ago in February of 1999, Williams defeated the Australian Open runner-up Amelie Mauresmo 2-6, 6-3, 7-6(7-4) in the final of the Open Gaz de France in Paris to win her first professional singles title.
This year Williams won a record $6,545,586 in WTA Tour prize money.