The Boston Red Sox announced they had placed closing pitcher Kenley Jansen on the COVID-19 list after testing positive for the virus on Wednesday, September 13.

The 35-year-old will have to sit for at least seven days, with Chris Martin and John Schreiber likely to split closing duties for the team indefinitely.

The four-time MLB All-Star was reported to be under the weather since Friday, and he suddenly exited the second game of a one-day doubleheader against rivals New York Yankees on Tuesday evening.

The team initially said that Jansen left the game due to fatigue and illness symptoms.

"He was a little bit dizzy. They're checking on him so we'll see where we're at with him," Red Sox manager Alex Cora told reporters after the game.

Jansen, the Red Sox's only representative in the 2023 MLB All-Star game, departed in the ninth inning after throwing 13 pitches.

Kenley Jansen's All-Star campaign

The Curacaoan is currently in his first season with the Red Sox, and it has been a solid one, making 51 relief appearances while posting a 3.63 ERA and recording 29 saves.

The two-time NL Reliever of the Year played for the Atlanta Braves last season after more than a decade with the Los Angeles Dodgers from the 2010 to 2021 campaigns.

Jansen led the National League in saves in 2017 and 2022.