Bob Gibson, who won 251 games during a Hall of Fame career with the St. Louis Cardinals, is receiving treatment for pancreatic cancer.
Gibson's condition was reported for the first time on Saturday by the St. Louis Post-Dispatch.
The 83-year-old, who starred in Omaha Tech High and later Creighton, was diagnosed with a pancreatic center several weeks ago, his long-time agent Dick Zitzmann told the Post-Dispatch.
Gibson has been hospitalized in Omaha for the past two weeks, Zitzmann said. He has also visited the Johns Hopkins Hospital in Baltimore.
According to Zitzmann, Gibson will probably start chemotherapy Monday in Omaha.
The news of Gibson's condition was made public on Saturday, when Hall of Fame pitcher Jack Morris, airing a game for the Minnesota Twins, said he received a notice about Gibson.
Gibson pitched for the Cardinals from 1959 to 1975. He still holds club records for wins, complete games, shutouts and strikeouts.
He won the National League Cy Young and the MVP in 1968, when he went 22-9 with a 1.12 ERA and 13 shutouts.
Bob Gibson was a versatile athlete at Tech High, participating in baseball, basketball and athletics.
Bob Gibson, of Omaha Tech, played basketball at Creighton University in 1955 and in the summer he joined Bob Boozer on the Y Travelers team coached by his older brother Josh.
The Creighton basketball player, Bob Gibson, divides the defenders Don Poppen, left, and Jerry Kreykes, in 1956.
The president of the Creighton Alumni Association, Jim Green, introduces Bob Gibson to a clock and pen, voted the most valuable Bluejay in 1956.
Bob Gibson suffers a broken leg in batting practice after an accident in 1962.
Bob Gibson and Cardinals manager Johnny Keane in the spring of 1963 before the fifth season of Gibson.
Bob Gibson pitcher of the St. Louis Cardinals escapes from a flying bat after a slip in a third-stroke hit in 1964.
The new World Series MVP, Bob Gibson, left a plane at the Eppley Airfield, starting "Bob Gibson Day" in Omaha in 1964.
Bob Gibson stops to throw a ball to a young man who was equipped with a mask and a catcher glove while the children lined the streets in 1964 after Gibson was named World Series MVP.
Bob Gibson, left, with Gale Sayers at Near North YMCA in 1965.
St. Louis Cardinals' Bob Gibson pitcher is congratulated by catcher Tim McCarver and third baseman Mike Shannon after his three-hit 7-7 victory over the Boston Red Sox to win the 1967 World Series.
The ace of St. Louis Cardinal, Bob Gibson, throws a tear from his eye after receiving a huge gold key and a hand-made replica of a baseball and a glove from Lake School students in 1967.
Bob Gibson when he set a World Series record by striking out 17 Detroit Tigers on October 2, 1968.
St. Louis Cardinal Bob Gibson in 1971.
The Hall of Fame of the St. Louis Cardinals, from left to right, Bob Gibson, Stan Musial, Lou Brock and Ozzie Smith pose for a photograph during the pre-game ceremonies, before the first day of play in 2003.
Bob Gibson, a native of Omaha and former player of the St. Louis Cardinals, poses in front of Bob Gibson's statue after an opening ceremony outside of Werner Park.
Former Major League pitcher and Omaha native Bob Gibson spoke at the 2013 Bob Gibson Heritage Project banquet.
From left to right, Bob Gibson, Marlin Briscoe, Johnny Rodgers and Ron Boone pose for a photo during a special dinner "A Night with the Magician" in honor of Marlin Briscoe in 2016.