PITTSBURGH -- The Steelers' tight end depth is tight, at least for now.

Third-year tight end Xavier Grimble underwent surgery to repair a torn ligament in his right thumb/wrist area, according to a source. Grimble hopes to return for Week 1 but will most likely miss the rest of the preseason. He suffered the injury in a practice and did not play in Thursday night's loss at Green Bay.

Grimble has 16 catches for 150 yards and three touchdowns from 2016-17 as the team's No. 3 option at the position.

Starter Vance McDonald missed most of training camp with a foot issue that will likely keep him out of Saturday's preseason matchup against Tennessee, leaving Jesse James as the only healthy tight end with an NFL catch. Free agent pickup Bucky Hodges is a good pass-catcher but considered raw as a blocker, while Pharoah McKever is an undrafted free agent and Christian Scotland-Williamson is a rugby star turned practice-squad project as part of the NFL's international program.

Coach Mike Tomlin labels all team injuries as "day-to-day" and doesn't have a concrete plan for tight end distribution because of the time of year.

"It's just those that are available, developing, working their skills relative to their position," Tomlin said. "We're very much still in training camp mentality."

The Steelers have big plans for tight ends in new coordinator Randy Fichtner's offense. Tight ends are lining up wide more often, for example.

"We're expecting to grow as a position, make the most of the year," said James, who led all Steelers tight ends with 43 catches in 2017.