BOSTON — Mookie Betts hit three home runs against James Paxton during the first four innings Friday night of a 10-5 rout over the New York Yankees, whose starting pitchers have stumbled this week in historic fashion.

Betts homered on Paxton’s eighth pitch in a three-run first that included J.D. Martinez’s two-run homer, went deep again leading off the third for a 4-0 lead and hit a two-run drive in the fourth for a 7-0 advantage.

Betts added an RBI double in the sixth off David Hale to give him five RBI and grounded out in the eighth. With his fifth career three-homer game, Betts raised his season total to 18 homers.

Batters have had three-homer games on four straight days for the first time in big league history. Betts followed the New York Mets’ Robinson Canó, St. Louis’ Paul DeJong and Minnesota’s Nelson Cruz.

Andrew Cashner (10-5), coming off losses in his first two starts after Boston acquired him from Baltimore, allowed three runs and 10 hits in 6 2/3 innings.

Martinez had three RBI for the Red Sox, who won the opener of the four-game series 19-3 and have pulled within nine games of the AL East-leading Yankees. The Red Sox had 14 hits, giving them 37 in the first two games of the series, and reached 11 games above .500 for the first time this season at 58-47.

Paxton (5-6) became just the fourth pitcher in big league history to allow a leadoff home run in three straight starts, according to STATS, after Brad Radke (2004), Brandon Backe (2008) and Yovani Gallardo (2017). Colorado’s Charlie Blackmon went deep off Paxton to start last Sunday and Tampa Bay’s Travis d’Arnaud did the same on July 15.

Paxton has an 11.00 ERA in the first inning this year, allowing 10 first-inning home runs in 18 starts. Overall, he allowed seven runs and nine hits in four innings, including a career-worst four homers, striking out nine and walking none. His ERA rose to 4.72 and he has allowed 17 homers this season, including 11 in his last six starts.

New York has allowed 64 runs in its last six games, the most allowed by the Yankees in a six-game span. Yankees starters gave given up 47 runs — 43 earned — in that span, yielding 47 hits in 21 2/3 innings — including 16 homers. New York became the first team in the live ball era since 1920 whose starters allowed six or more runs in four innings or fewer in six straight games, according to STATS.

Austin Romine had three hits and drove in a pair of runs for the Yankees, who have lost 4 of 6. New York didn’t score off Cashner until the sixth.