Carolina Panthers owner Jerry Richardson has been readmitted to the hospital, a month after undergoing surgery to install a pacemaker.
Spokesman Charlie Dayton said Saturday the pacemaker is working fine, but doctors planned further tests to determine why Richardson has been feeling ill.
The 72-year-old Richardson has had a history of heart problems and underwent quadruple-bypass surgery in 2002.
Richardson in 1993 became the first former NFL player since George Halas to become a team owner when the NFL awarded an expansion franchise to Richardson. The former Colts receiver caught a touchdown pass from Johnny Unitas to help Baltimore win the 1959 NFL championship.
Richardson and his sons manage the Panthers and Bank of America Stadium.