STANFORD -- Josh Nunes, the Stanford quarterback who replaced Andrew Luck at the start of last season, has retired because of an undisclosed medical condition, the school announced Monday in a Twitter post.

Although the school did not list a reason for the "medical retirement," Nunes missed all of spring practice after suffering a biceps muscle injury to his throwing arm while lifting weights in January.

Coach David Shaw sounded concerned after the Cardinal's spring game this month.

"Josh Nunes's situation is not a short-term deal," Shaw said at the time. "He may not be back for training camp. I'm hoping that he comes back, period. We'll see."

Nunes started the first nine games last season before Shaw switched to redshirt freshman Kevin Hogan against Colorado. Hogan led Stanford to the Pac-12 championship and a Rose Bowl victory over Wisconsin.

His departure, coupled with Brett Nottingham's transfer last December, means Evan Crower and Dallas Lloyd will compete for the No. 2 job.

Nunes will be able to remain on scholarship to finish school but he won't count against the limit of 85 scholarships under NCAA rules for medical retirements.

Stanford also announced via Twitter that senior fullback Geoff Meinken retired. He missed all of last season with a knee injury and suffered a setback during the spring game. Ryan Hewitt is listed as the starting fullback with Lee Ward and Patrick Skov as backups.

In other Stanford football news, the school announced that senior fullback Geoff Meinken has decided to graduate this spring and will not return for a 5th year due to a knee injury.

Men's golf

No. 1 Cal has a nine-shot lead over second-place and host No. 3 UCLA after the opening day of the 2013 Pac-12 Championship. Stanford is fourth.

The Golden Bears' performance was highlighted by Max Homa (61-70 — 131, -9), who has a three-shot lead on teammate Michael Weaver (65-69 — 134, -6) and broke the course record in the opening round with a nine-under par 61 at the par-70, 7,236-yard North Course at the Los Angeles Country Club.

Women's golf

San Jose State, Stanford and Cal will be among the 24 teams playing at the NCAA West Regional May 9-11 at the Stanford Golf Course.

The top eight teams from the West Regional advance to the NCAA Championship, May 21-24 at the University of Georgia Golf Course in Athens, Ga. The top two individuals, not on an advancing team, also advance to the championship.