How long might Matthew Stafford's hamstring injury sideline the Rams quarterback?

It’s only hamstring tightness. Nothing that will keep Matthew Stafford from practicing next week, coach Sean McVay said.

But should the Rams and their fans be worried about their 36-year-old quarterback?

On Thursday, for the second day in a row, Stafford was sidelined.

During a joint practice with the Dallas Cowboys on Wednesday, Stafford ran the offense for three series before he was pulled because of the hamstring issue.

On Thursday, he was not on the field for a jog-through.

“He just felt a little something,” McVay said, “so we were just being smart with it.”

Sounds reasonable.

Stafford endured broken bones, sprains, elbow issues, concussions, spinal contusions and other injuries throughout his 15-year career. So hamstring tightness more than three weeks before the season opener at Detroit probably does not register as a major concern.

Yet ...

Stafford’s situation, combined with other injuries suffered by starters, cannot make McVay feel comfortable as the Rams prepare for the Lions .

Receiver Puka Nacua , linemen Alaric Jackson, Jonah Jackson and Rob Havenstein and cornerback Darious Williams remain out and McVay has provided no timetable for their return.

On the positive side, their absence has enabled young players such as lineman Warren McClendon Jr. and rookie receiver Jordan Whittington to get more snaps with the first-team offense.

Stafford’s hamstring issue also helped backup quarterback Jimmy Garoppolo get work with the first-team offense during the second half of the practice with the Cowboys and during the jog-through Thursday.

Those snaps are important because Garoppolo is suspended for the first two games of the season and probably won’t play in the preseason.

But the longer Stafford and other starters remain sidelined, the longer McVay and his staff must wait to get a real look at how the offense and defense function as units.

Etc.

Receiver Cooper Kupp was given a rest day. … Nacua did rehab work with a trainer on the sideline. ... Aubrey Pleasant, the assistant head coach, will be on the sideline as the head coach against the Chargers, McVay said. McVay will be in the coaches’ booth.

This story originally appeared in Los Angeles Times .