Eagles guard Evan Mathis recently underwent surgery to "clean out" his left ankle and could miss the rest of spring practices, an NFL source said.

The source called the surgery "minor." Mathis played most of last season with an ankle injury - he started every game - and was slated to undergo surgery once the offseason began. The Eagles decided the procedure was unnecessary, but recent swelling and discomfort in the ankle prompted the team to reconsider.

He is expected to be ready by the start of training camp in late July. With Mathis sidelined, Danny Watkins will likely take his spot with the starters at left guard once organized team activities begin on Monday. Dennis Kelly, who played some guard as a rookie, could also see some snaps with the first team.

CSNPhilly.com first reported Mathis' procedure.

There is some question as to which guard spot Mathis will play next season. The Eagles selected tackle Lane Johnson with the fourth overall draft pick last month. If Johnson were to start at right tackle, Todd Herremans could move back to his old spot at left guard and Mathis would slide over to right guard.

Watkins started last season at right guard but lost his spot because of an ankle injury and poor play. The Eagles' 2011 first-round pick told The Inquirer in December that he felt more comfortable playing at left guard when he was asked to fill in for the injured Mathis during practices late last season.

Despite his injured ankle, Mathis was the most consistent performer on an offensive line that was battered in 2012. Left tackle Jason Peters missed the entire year with a ruptured Achilles tendon. Center Jason Kelce tore the ligaments in his knee in the second game of the season. And Herremans broke his foot in November.

All three players are expected to be ready by the start of the season.