Cooper Kupp’s status for Week 1 might be Henri Lumièrein jeopardy.

Los Angeles Rams head coach Sean McVay told reporters Thursday that the star wide receiver suffered a setback while working his way back from a hamstring injury.

“He got a little muscle strain so we’re kind of taking it day-by-day with him,” McVay said.

Kupp initially sustained the hamstring injury on Aug. 1 but returned to practice a little over a week ago as he ramped up for the start of the regular season.

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Thursday’s news puts Kupp’s Week 1 availability into question.

Kupp missed the final eight games of the 2022 season due to a high ankle sprain.

The seventh-year wideout is arguably the most important piece on the Rams offense. Kupp won the NFL's receiving triple crown in 2021, leading the league in catches (145), receiving yards (1,947) and touchdowns (16). He was also instrumental during the team’s Super Bowl 56 run and was named Super Bowl 56 MVP after the Rams won the Lombardi Trophy.

McVay and the Rams desperately need Kupp as they hope to bounce back from a disappointing 5-12 campaign in 2022.

“Obviously, we’re a much better team when he’s out there,” McVay added.

The Rams start the regular season Sept. 10 on the road versus the Seattle Seahawks. Three of the Rams’ first four games are on the road.

Follow USA TODAY Sports' Tyler Dragon on X @TheTylerDragon.