BOSTON -- Doctors remained optimistic Tuesday even as baseball great Ted Williams was back under sedation in intensive care a day after he underwent a lengthy operation to repair failing heart valves.

Doctors at New York Presbyterian Hospital's Weill Cornell Medical Center were encouraged by Williams' response to doctors commands immediately after surgery, The Boston Globe reported.

The 82-year-old Hall of Famer, baseball's last .400 hitter, could not speak when he awoke from surgery because he was still intubated, but he did respond to doctors' commands, said Dr. Jeffrey Borer, the cardiologist overseeing the Williams case.

"When he was told to squeeze a doctor's fingers he did it, and that's very important," Borer told the Globe in a story to be published in its Wednesday editions. "To be able to respond to a command while you're sedated after an operation requires a very high-level and complicated neurological response."

"I think things went well," said Dr. Wayne Isom, head of the 13-man surgical team, after Monday's nine-hour operation. "The next 48 hours is the critical period. It'll be touch and go, but I'm an optimist."

The hospital has declined to give out information at the family's request.

Williams is expected to remain in the hospital for the next 10-to-14 days.

Monday's procedure was unusually long because of excessive bleeding caused by medication Williams had been taking, Isom said. During the surgery doctors determined that repair to the damaged heart valve was too difficult and decided to repair the leaking valve with pig tissue.

Doctors also took longer than normal to stabilize Williams' heart after the surgery.

"It took several hours in the OR to deal with creating the optimal support system for him," Borer said.

Monday "was a hard day," Williams' son, John Henry Williams, told the Globe. "I kissed Dad on the forehead at 2:10 and didn't get that call until 9:45. As time went on, it was unnerving but I had a gut feeling that things would be OK."

Williams had a pacemaker inserted in November, but continued to suffer from shortness of breath, caused by the leaky heart valve.

Last Thursday, he entered a Florida hospital with what cardiologist Rick Kerensky described as "deterioration of his cardiovascular and neurological status." He was transferred to New York on Sunday.

Williams' last public appearance in Boston was when he threw out the ceremonial first ball at the 1999 All-Star game at Fenway Park.

He hit .406 in 1941 and had 521 career home runs, including a farewell homer in his last at-bat in 1960.