He withdrew during the first round of the U.S. Open after hitting a shot to the 12th green. At that point, he had a severe spasm and had to be carted off the course by medical personnel.
Irwin, who won the 1998 and 2000 U.S. Senior Opens, is coming off back-to- back 11th place finishes. The 11th-place finish in the 2001 Open snapped a streak of six consecutive top-five finishes in his first six U.S. Senior Open appearances.
Irwin, who is the all-time leading money winner at this event, tied for fifth in his first Senior Open in 1995 and followed that with a runner-up finish the following year. After another fifth-place showing in 1997, he won his first Senior Open the following year. In 1999, he tied for third before winning again the next year.
The U.S. Senior Open will be contested at the Inverness Club. Irwin was replaced in the field by Jim Whisman, an amateur from Claremore, Oklahoma.