WEST SACRAMENTO, Calif. (Interstat) — Ceddanne Rafaela hit a grand slam in the sixth inning to lift the Boston Red Sox to a 4-2 victory over the Athletics on Monday night at Sutter Health Park.

Rafaela’s blast to left-center field cleared the bases and erased a one-run deficit, giving Boston a lead it never relinquished. The Red Sox improved to 55-50, while the Athletics fell to 44-62.

Tyler Soderstrom put the Athletics ahead in the first inning with a solo home run, his 17th of the season, a fly ball to left-center. That 1-0 lead held until Boston’s decisive sixth.

Connor Wong started the rally with a sharp double to left. After Masataka Yoshida grounded out and Anthony Seigler grounded out, moving Wong to third, Willson Contreras walked and Wilyer Abreu walked to load the bases. Rafaela then connected for his 11th homer of the year, scoring Wong, Contreras and Abreu.

The Athletics answered in the bottom half when Jonah Heim led off with a solo homer to center, his 10th, cutting the margin to 4-2. But Boston’s bullpen held firm from there.

Payton Tolle earned the win, improving to 6-6. Aroldis Chapman notched his 25th save of the season, striking out two in the ninth. Jack Perkins took the loss, falling to 2-6. He allowed two earned runs on one hit in 5 2/3 innings, walking two and striking out four. José Suarez gave up two earned runs on two hits in one-third of an inning.

Elvis Alvarado pitched a scoreless inning of relief for the Athletics, allowing two hits with one strikeout. Hayden Juenger also threw a scoreless inning, giving up no hits.

Colby Thomas had two of the Athletics’ six hits. Heim finished 1-for-4 with the home run and an RBI. Soderstrom was 1-for-3 with the homer and an RBI. Alika Williams went 1-for-4, and Jeff McNeil was 1-for-3. Tommy White went 0-for-4.

For Boston, Wong doubled and scored. Rafaela’s grand slam was the only extra-base hit among the Red Sox’s five hits. Jarren Duran went 0-for-4, while Andruw Monasterio doubled in the seventh.

The game drew 10,486 fans and lasted 2 hours, 35 minutes.

Boston entered the game having won six of its previous seven games, including a 6-1 victory over Toronto on Sunday. The Athletics had lost two of three to Minnesota before this contest.

The two teams meet again Tuesday at Sutter Health Park in the second game of this four-game series. The Red Sox then travel to Los Angeles to face the Dodgers, while the Athletics return home to host Detroit after the series.

Interstat’s game simulator had projected a final score of Boston Red Sox 7, Athletics 3. Interstat’s ELO system had projected Boston with a 62.50 percent probability to win. Boston had been installed as a pregame favorite with a spread of minus-1.5. The total score of 6 went over the over/under line of 9.5.