New York Mets first baseman Pete Alonso hit his 40th home run of the season on Sunday to set the National League rookie record for home runs in a season.

Alonso homered to left field in the ninth inning. The 418-foot blast off the Kansas City Royals' Jacob Barnes broke a tie with the Los Angeles Dodgers' Cody Bellinger for most home runs by a NL rookie in a season.

Bellinger hit 39 home runs in 2017.

"It's crazy," Alonso said after the Mets' 11-5 victory when asked about setting the record. "I just gotta go back to the days of spring training when I didn't know if I was gonna make the team out of camp or not. I'm just extremely thankful for this opportunity, and this has been such an incredible year. I just wanna keep building and help this team win."

Alonso is the first Mets player to hit 40 home runs in a season since Carlos Beltran in 2006.

With the home run, Alonso improved to 3-for-4 in the Mets' victory over the Royals, with three runs and two RBIs.

The victory pulled the Mets (64-60) into a three-way tie in the NL wild-card chase, 1½ games behind the Chicago Cubs, who hold the second wild-card spot.

The New York Yankees' Aaron Judge holds the major league record for home runs in a season by a rookie, with 52 in 2017.