BOSTON (Interstat) — Sonny Gray pitched six scoreless innings, Andruw Monasterio drove in the game’s only run with a sixth-inning single and the Boston Red Sox edged the Cleveland Guardians 1-0 on Wednesday night at Fenway Park. Gray allowed four hits, walked one and struck out three while improving to 18-5. He tied Philadelphia’s Cristopher Sánchez for the major league lead in victories and is in line to become the fourth Red Sox pitcher since 2000 to lead the American League in wins, joining Rick Porcello in 2016, Josh Beckett in 2007 and Curt Schilling in 2004. Aroldis Chapman struck out the side in the ninth for his 35th save. Boston snapped Cleveland’s six-game winning streak and won for just the fifth time in 13 games. The Red Sox clinched a playoff spot on Sunday.

Cleveland starter Foster Griffin was nearly as effective, working six innings and allowing one earned run on 10 hits while striking out seven. He fell to 15-6. Boston collected 12 hits to Cleveland’s five, but the Red Sox struggled to cash in until the sixth. Cleveland grounded into two double plays and left several scoring chances unfulfilled. The Guardians’ best early opportunity came in the third, when Patrick Bailey singled and Petey Halpin flew out before Brayan Rocchio grounded into an inning-ending double play. Another threat in the eighth ended when Chase DeLauter grounded into a double play after Rocchio singled and José Ramírez walked. Cleveland also got a leadoff single from Steven Kwan in the fourth and a two-out single from Halpin in the fifth, but neither runner advanced past first.

Boston had early traffic against Griffin. In the first, Jahmai Jones and Wilyer Abreu singled, but Adley Rutschman grounded out. Gray retired the first three Cleveland batters on a lineout to center and two flyouts to center. In the second, Ceddanne Rafaela singled and Caleb Durbin reached on a fielding error by Ramírez, but Trevor Story struck out and Monasterio grounded into a double play. Boston loaded the bases in the third on singles by Roman Anthony, Nick Sogard and Rutschman, but Jahmai Jones, Abreu and Jarren Duran all struck out to end the inning. The Red Sox also put two runners on in the fifth, only for Rutschman to line out to left. Boston’s inability to convert with runners in scoring position kept the game scoreless into the middle innings.

The game turned in the sixth. Jarren Duran singled with one out, moved to second on Durbin’s groundout and scored when Monasterio lined a single to left field. Roman Anthony struck out to end the inning, but the lone run was enough for Boston’s bullpen. Tyron Guerrero followed Gray with a scoreless seventh, striking out three and walking one. In the seventh, Nick Sogard and Jahmai Jones struck out before Abreu singled and Rutschman struck out. Garrett Whitlock worked around a hit and a walk in the eighth, and Chapman finished with a perfect ninth. Chapman struck out Jo Adell, Angel Martínez and Angel Genao in order. The save was Chapman’s 35th of the season.

Cleveland’s bullpen kept the deficit at one. Shawn Armstrong, Matt Festa and Tim Herrin combined for 2 1/3 scoreless innings. Herrin struck out three in his inning. Steven Kwan had two hits for Cleveland, while Monasterio finished 1 for 3 with the game’s only RBI. The Guardians had five hits overall and could not solve Gray or the Boston relief corps. In the bottom of the eighth, Duran singled, advanced to third on Durbin’s flyout to right and was stranded when Story and Mickey Gasper grounded out. Boston improved to 85-73, while Cleveland fell to 82-76. The Red Sox have clinched a playoff spot and remain in position to improve their postseason seeding. The Guardians, who had won six straight, remain in the playoff chase despite the low-scoring loss.

Gray’s recent form included a win at Texas on Sept. 17, when he allowed three earned runs over 6 1/3 innings, and a loss to Kansas City on Sept. 11, when he allowed three earned runs over six innings. Against Cleveland, he was sharper. Griffin retired Cleveland in order in the second on a flyout, a strikeout and a popout, and he worked around a two-out walk in the fourth by striking out Bazzana. He matched Sánchez for the major league lead in wins and became the fourth Red Sox pitcher since 2000 to lead the American League in victories, joining Porcello, Beckett and Schilling. Gray’s outing also gave Boston’s bullpen a lead to protect. Guerrero, Whitlock and Chapman combined for three scoreless innings, allowing one hit and two walks while striking out seven. Chapman’s ninth inning was his most dominant stretch of the night.

The game took 2 hours, 35 minutes and drew 36,360 fans to Fenway Park. Cleveland pitchers combined for 13 strikes, 32 balls and 13 balls in play. Boston pitchers combined for 16 strikes, 27 balls and 16 balls in play. The teams will conclude the series Thursday at Fenway Park before Cleveland travels to Kansas City and Boston hosts the Chicago Cubs. Boston’s win evened the series after Cleveland won 3-2 on Tuesday. Cleveland entered having won six straight, including a 3-2 victory at Boston on Tuesday, while Boston had lost five of six. Cleveland’s previous six wins included victories over the Athletics, Chicago White Sox and Minnesota Twins.

Interstat’s game simulator had projected a final score of Cleveland 8, Boston 7. Interstat’s ELO system gave Boston a 58.1 percent probability to win. Boston had been installed as a pregame favorite with a spread of -1.5. The total score of one run finished below the over/under line of 7.5.