-- SAN DIEGO -- San Diego Chargers general manager Tom Telesco confirmed on Thursday that rookie defensive end Joey Bosa suffered a minor hamstring injury and likely will not play in the team's season opener on the road against the Kansas City Chiefs.
Telesco made those comments in an interview on XTRA 1360 Fox Sports Radio in San Diego.
"Obviously, we're not optimistic right now," Telesco said. "It truly is a day-to-day injury. It's a minor hamstring, and our goal is to make sure it doesn't turn into something long-term."
Telesco went onto say the Chargers have been preparing other players to perform in Bosa's absence since the Ohio State product remained unsigned at the start of training camp on July 29.
"I know Joey's desire to play is very, very high, but we need to be smart about it, too," Telesco said.
After ending a 31-day holdout by signing a four-year deal with the Chargers last week, Bosa practiced only once on Tuesday in a jersey and shorts because of the hamstring injury.
Bosa missed both of San Diego's padded practices this week because of the injury, and remains on the NFL exempt list. He would have to be added to the active roster by Saturday to play in the team's game Sunday against Kansas City.
The Chargers are taking a long-term approach to Bosa's availability this season, making sure he's fully capable to carry out his assignments physically and mentally on the field.
San Diego had to deal with rookies being out extended periods of time the past two seasons because of lingering, minor injuries.
Last season, third-round selection Craig Mager missed five games with a hamstring issue. And two years ago, outside linebacker Jeremiah Attaochu missed a total of five games, also because of a hamstring issue, after trying to come back too early.
"For us, we have to make sure that we don't try and put four weeks of work into two or three days," Telesco told the team's website. "So we have to be smart with this and gradually move him into the process.
"He does have some work to do. The playbook part is not the hardest thing. But the on-field part, as far as taking the playbook and putting it on the field -- making moves and reactions in real time against an offense with teammates next to you, that does take some time in this scheme. But we'll get there. It's still early."