The Boston Red Sox offense was held in check by Kansas City Royals rookie pitcher Brad Keller through the first four innings of Saturday night's game at Kauffman Stadium, but the Boston offense came alive with four runs in the fifth to overcome an early deficit en route to a 15-4 victory.

Keller yielded just four hits through the first four innings as the Royals built a 3-0 lead with a run off Red Sox pitcher David Price in the second and two more in the third.

The Red Sox scored their first run of the game on a J.D. Martinez RBI single to left field in the top of the fifth. Boston took the lead on Xander Bogaerts' three-run double to center field later in the inning.

Christian Vazquez knocked in a pair of runs with a line drive single to center field in the seventh. Vazquez fractured the pinkie finger on his throwing hand while stealing second in the same inning.

"He's going to go on the DL," Red Sox manager Alex Cora said. "He got some X-rays, but when we go to Boston, we'll do more testing and all that."

The Red Sox blew the game wide open with seven runs in the ninth. Mookie Betts, who had four hits in the game, drove in a run with a double on a ground ball to left field. Betts came around to score on a double by Andrew Benintendi, who swatted a solo home run in the eighth.

Sandy Leon capped the scoring with an RBI single on a sharp ground ball to right field.

Price lasted just 4.2 innings, allowing four runs on six hits and one walk while striking out nine.

He departed after hitting three batters in the fifth, including Lucas Duda with the bases loaded. Hitting Duda forced in the tying run and tied an MLB record for the most hit batsmen in one inning. The most recent pitcher to do it was John Lackey, as a member of the Chicago Cubs in July, 2017.

The Red Sox bullpen thrived after Price's departure, as five relievers combined for 4.1 innings of no-hit ball. Joe Kelly recorded just two outs before he experienced lightheadedness and left the game. An update on his condition was not immediately available.

Boston records its MLB-best 61st win and maintains its two-game lead over the New York Yankees in the AL East. The Red Sox have won five in a row and are 6-2 on their current road trip.