Serena Williams is celebrating down under -- for the fifth time.
Williams, 28, defended her 2009 Australian title against Henin, winning in three sets 6-4, 3-6, 6-2 at Rod Laver Arena in Melbourne.
She lost the Open in 2008 but won in each previous odd-numbered year since 2003, taking home the 2003, 2005 and 2007 titles in Australia.
Williams, a 12-time Grand Slam singles champion, competed in the tournament alongside sister Venus Williams, who was upset by Chinese player Li Na in the quarterfinals. Serena Williams defended Venus' honor in the semis, knocking the Chinese player out in straight sets.
Henin, herself a seven-time Grand Slam winner, quit professional tennis after the 2008 Australian Open while still holding the No. 1 ranking. She announced last fall she would rejoin the sport.