"Dominic pull his (pectoral) muscle off his bone," Tedford said.
Galas, a redshirt senior from Modesto (Calif.) Central Catholic, was scheduled to undergo surgery Tuesday afternoon. There is not an exact timetable for his return until doctors can determine the severity of the injury, but Tedford indicated the standard recovery time would have Galas back by midseason.
"Initially they talked about maybe three months for rehab, which would put him somewhere I believe in the October range," Tedford said.
After starting all 13 games last season at center, Galas was projected to start at right guard despite missing all of spring practice because of injury. He has played in all 38 games over the past three seasons after redshirting in 2008.
Redshirt sophomore Geoffrey Gibson was listed as Galas' backup on the post-spring depth chart.
Dan Greenspan is the publisher of Cal Sports Digest and covers the Pac-12 for Fox Sports/Scout.com. Follow him on Twitter @DanGreenspan.