Former NFL star Terry Bradshaw is scheduled to undergo more tests to determine the cause of chest pains that forced him to miss his last two assignments on CBS.

"He had some tests last week, and he's going to have some more this week," network spokeswoman Sandy Genelius said Sunday.A Pittsburgh television station, KDKA, reported that a tumor was found behind Bradshaw's heart during tests at a Dallas hospital.

Bradshaw, 40, denied the report. The former Steelers quarterback told CBS that he doesn't know the cause of the ailment.

"He emphasized that there has been no diagnosis," Genelius said.

Genelius said Ted Shaker, executive producer of CBS Sports, spoke to Bradshaw on the phone Sunday.

"He (Bradshaw) sounded great," she said. "He was in very good spirits. He was even making jokes."

Bradshaw retired from football after the 1983 season.