CHICAGO (AP) _ Ron Santo, a former nine-time All-Star third baseman for the Chicago Cubs who became the team's radio commentator 10 years ago, showed improvement Tuesday following a mild heart attack.

Santo, 59, rested overnight at a Denver hospital and was no longer experiencing chest pains, the team said.

Abnormalities in his heart's rhythm were being treated with medication, and he may be transferred out on intensive care by Thursday.

Santo, who hit .277 during a 15-year major league career, was admitted to Rose Medical Center in Denver on Monday.

Former Santo teammate Randy Hundley will replace him in the Cubs' radio booth on Thursday when the team finishes a three-game series with the Colorado Rockies.

Santo has a history of diabetes and recently underwent an angiogram that revealed a minor blockage of one artery.