PITTSBURGH -- Jake Guentzel's scorching start for the Pittsburgh Penguins has come to an abrupt halt.

The team said Wednesday that the star forward is "week to week" with an upper-body injury. Coach Mike Sullivan did not go into detail about how or when Guentzel was hurt. Guentzel left the ice briefly in the first period of a victory over Seattle on Monday night, though he returned and finished with two goals and an assist.

"It's next man up, as we've had for a few years now, it's no different," defenseman Marcus Pettersson said. "New guys have to step up. New opportunities. So we'll see what happens."

Guentzel has been among the most productive players in the NHL over the opening two months of the season. He has a 13-game points streak, a span that includes 11 goals -- with a hat trick against Vancouver last week -- and seven assists. The 27-year-old has 15 goals and 12 assists in 24 games for the Penguins, who are in fourth place in the Metropolitan Division.

Kasperi Kapanen will likely get the first crack at replacing Guentzel on the top line alongside center Sidney Crosby and Evan Rodrigues, who is filling in for an injured Bryan Rust. Kapanen, who has five goals in 25 games, has floated up and down the lineup lately.

"Those are pretty big shoes to fill, obviously," Kapanen said. "Jake's been one of our best players, if not our best player, for a long period now."

The Penguins, who have won seven of 10, finish a five-game trip on Friday night at Washington.