PERTH, Australia -- Americans Sloane Stephens and John Isner are confident of playing in the Australian Open despite withdrawing from their final Hopman Cup matches against the Czech Republic with injuries.

Stephens retired Friday with a sore left wrist after losing the first set of her match to Petra Kvitova 6-3. She will have scans to rule out any serious injury and plans to compete at next week's Sydney International before traveling to Melbourne for the Australian Open, which starts Jan. 13.

Isner, who missed last year's Australian Open with a knee injury, withdrew from his singles match against Radek Stepanek with a right ankle injury he sustained in training.

Isner said Saturday that "hopefully I can get fit and get ready for the Australian Open."