Orioles shortstop Gunnar Henderson, left, tags out Boston’s Justin Turner, who was trying to steal second, during the Red Sox’s 5-1 loss on Saturday in Baltimore. Julio Cortez/Associated Press

BALTIMORE — Ryan Mountcastle hit a tiebreaking double in the seventh inning and scored on an infield hit to lead the AL East champion Baltimore Orioles over the last-place Boston Red Sox 5-2 on Saturday night for their 101st win.

Baltimore (101-60), which hosts an AL Division Series starting Oct. 7, is finishing its winningest season since going 102-57 in 1979.

After Kutter Crawford allowed one hit in six innings, Josh Winckowski (4-4) gave up a single to Adley Rutschman leading off the seventh. Pinch-runner Jorge Mateo stole second standing up, and Mountcastle doubled to right with two outs for a 1-0 lead.

Heston Kjerstad’s infield single that second baseman Pablo Reyes couldn’t field enabled Mountcastle to score from second.

Bruce Zimmermann (2-0), recalled from Triple-A Norfolk earlier in the day, pitched two scoreless innings in relief of Kyle Gibson, who allowed seven hits in five scoreless innings.

Trevor Story’s RBI single infield single against Jack Flaherty in the eighth cut Baltimore’s lead to 2-1. Before Story’s hit, Boston (77-84) had 10 hits without scoring.

The Orioles added three runs in the eighth on Mateo’s forceout that scored Jordan Westburg and Anthony Santander’s two-run single.

Crawford struck out seven without walking a batter.

Masataka Yoshida singled in a ninth-inning run.

TRAINER’S ROOM

Red Sox: RHP Kenley Jansen, who was activated from the COVID-19 injured list on Sept. 23, won’t pitch again. He hasn’t appeared since Sept. 12.

Orioles: RHP Félix Bautista, who hasn’t pitched since Aug. 25, will undergo Tommy John surgery next month. He’s expected to return for the 2025 season.