PHILADELPHIA -- Philadelphia Eagles tight end Zach Ertz had surgery Friday to repair a torn "core muscle," the team announced.
A league source told ESPN's Adam Caplan that Ertz had suffered a groin injury. Dr. William Meyers, who did surgery on Houston Texans running back Arian Foster last week, performed Ertz's procedure.
Ertz, 24, was slow to get up after a collision in practice Wednesday. He left the field before his teammates after that practice and did not practice the following day.
Eagles coach Chip Kelly said he expected Ertz to be ready for the regular-season opener Sept. 14, but said that the tight end would likely miss the entire preseason.
Ertz caught 58 passes for 702 yards and three touchdowns in 2014. He started five games.
Brent Celek has been the Eagles' starting tight end due largely to his superior blocking ability. Ertz worked hard on his blocking this offseason in an effort to gain more playing time. Ertz spent time with Hudson Houck, the former Dallas Cowboys offensive line coach, and met with former tight end Anthony Gonzalez.
Ertz's offseason work made it seem likely he was poised for a breakout season. Now, the 2013 second-round pick will have to bounce back from surgery. Last year, Eagles center Jason Kelce had a sports hernia repaired by Meyers. Kelce missed four games before returning to the lineup.
Aside from Celek, the Eagles have Trey Burton at tight end. The release of James Casey has left the team a bit thin at the position.
After this year's draft, the Eagles signed undrafted free agent tight ends Andrew Gleichert, Eric Tomlinson and Justin Tukes.
"Daily, a different guy shows up," Kelly said. "Eric Tomlinson came out the last two days and made some big catches for us. All three of them have size. Andrew's a really sharp player -- really picked things up very quickly. And Justin Tukes is starting to really come along.
"One byproduct of not being able to have Zach for a couple of games in the preseason, it will give those guys an opportunity to show what they can do."