BRUSSELS, Belgium -- Kim Clijsters, ranked No. 3 in the world, pulled out of Belgium's Fed Cup matches against Australia on Sunday due to a shoulder injury.

Clijsters said she was suffering from a reoccurrence of muscle pain in her right shoulder that has troubled her for several weeks.

"I had a bad pain in my arm this morning," Clijsters said. "A pain I know well, it's better that I take a rest day."

Clijsters watched from the stands with her boyfriend and world No. 1, Lleyton Hewitt, as Belgium beat Australia 3-1.

Nicole Pratt of Australia beat Els Callens, who subbed for Clijsters, 6-2, 6-4 in the reverse singles match.