Los Angeles Dodgers pitcher Dustin May reacts after being hit in the head by a line drive in the fourth inning of a Major League Baseball game against the Arizona Diamondbacks (AFP Photo/Christian Petersen)

Los Angeles (AFP) - Los Angeles pitcher Dustin May walked off under his own steam after taking a line drive to the head in the Dodgers' 4-3 Major League Baseball win over the Arizona Diamondbacks in Phoenix.

The frightening moment came in the fourth inning of Sunday's game.

The 21-year-old rookie right-hander, instantly recognizable by his 6-foot, 6-inch frame and mop of red hair, was hit on the right side of the head by a drive off the bat of Jake Lamb.

May crumpled to the mound holding his head and lay there until medical personnel arrived. After several minutes he was able to walk to the Dodgers dug-out.

May said the ball grazed his glove before it hit his hand, slowing down a bit and mitigating the damage.

"When it hit me at first it really just frightened me," he said. "Then when I was on the ground, it was like, 'Well, dang, I wish that wouldn't have happened.'"

Dodgers manager Dave Roberts said May passed a concussion test but added that the team will "keep an eye on him in the days following."

"That's never a good situation," Roberts said. "I'm just happy it wasn't worse."

The Diamondbacks scored two runs on the bases-loaded play as the ball deflected into left field for a single.

The Dodgers, however, went on to win in 11 innings.

Cody Bellinger hit a game-tying homer in the ninth inning and Joc Pederson belted the game-winning home run in the 11th.