PARIS. Serena Williams is already assured a place in tennis history but her coach believes the 16-time grand slam champion will soon embroider her status among the greats.The American, who beat Maria Sharapova to win the French Open on Saturday, is now two grand slam titles shy of Chris Evert and Martina Navratilova’s tally of 18, and Patrick Mouratoglou believes Williams has the motivation to equal the mark."She needs two more titles and, yes, I think she’s going to get them,” Frenchman Mouratoglou told reporters after his charge beat Sharapova 6-4 6-4 at Roland Garros.The all-time record is held by Australian Margaret Court, who won 24 major titles, two more than German Steffi Graf, followed by Americans Helen Wills Moody (19), Evert and Navratilova (18)."When she is in the right state of mind, she is unbeatable,” added Mouratoglou, who celebrated his 43rd birthday on Saturday. "She is a huge champion, what more can I say?”The only thing that would prevent 31-year-old Williams from adding to her collection would be retirement. "It will only happen if her level of motivation goes down, and that is not the case today,” Mouratoglou said.When the American hoisted the Suzanne Lenglen Cup for the first time in 2002, little did she know she would have to wait until 2013 to experience the joy of winning the claycourt major again."After 11 years it’s incredible. I want to come back here and win again. I think I’m Parisienne,” a delirious Serena told the crowd in French after becoming the oldest woman to win the title since tennis went professional in 1968.The last time she triumphed at the spiritual home of claycourt tennis, the 31-year-old American turned out to be an unstoppable force as she went on to complete what she dubbed the "Serena Slam”.