Andy Pettitte continues to make progress on his way back from a broken leg, but he is not yet ready to throw off of a mound.

Pettitte had an X-ray on Sunday. The Yankees say it showed that his fractured left fibula continues to heal as expected.

The next step for Pettitte is to continue to throw off of flat ground and attempt to push off on his back leg with increased intensity.

Earlier, Pettitte hoped that he would be cleared to throw off of a mound after Sunday's X-ray, but he admitted that was "wishful thinking."

Pettitte is eligible to come off the disabled list Aug. 28, and said in the past that he would like to try and start throwing off a mound around Sept. 1.

But that timetable is now unclear.

Pettitte was asked about the latest date he could begin throwing off of a mound and still return to the Yankees. He did not have an answer.

It's also unclear when Pettitte will have another X-ray.

"I'm all X-rayed out," he said jokingly.

Pettitte recently said recently that he is being "overcautious" as he tries to work his way back to the rotation. The 40-year-old veteran fears that another setback could keep him from pitching again this season.

He suffered a setback in late July on a West Coast road trip, experiencing swelling in his leg. Pettitte estimated that it cost him about 10 days in his rehab.

"If I hadn't had a setback," Pettitte said, "I would be (on the mound)."