Watch: Rory McIlroy wins point vs. Maria Sharapova

(CBS/AP) A day after golfer Rory McIlroy ascended to No. 1 in the world for the first time in his career, he was back in front of fans hitting balls - tennis balls.

It happened last night at Madison Square Garden, where Maria Sharapova and Caroline Wozniacki (aka McIlroy's girlfriend) were playing an exhibition at the BNP Paribas Showdown.

With Wozniacki a game away from losing 6-3, 6-4 to Sharapova, she invited her boyfriend onto the court a day after the golfer won the Honda Classic in Palm Beach Gardens, Fla., to become the world's No. 1 for the first time.

"He wasn't too pleased with me," Wozniacki said later.

In jeans and a sweater, McIlroy showed off a one-handed backhand, and Sharapova hit his lob wide.

Asked if he was surprised to win the point, McIlroy said with a smile: "I've won a few off Caroline."

Wozniacki has been ranked No. 1 for 67 weeks in her career, though she's currently down to No. 4. McIlroy knows he'll need to stay on top for "another couple of years" to catch his girlfriend in that stat.