Alonso won $1 million of the $2.5 million prize pool.

"It means so much," Alonso said on ESPN.

Guerrero outlasted Joc Pederson of the Los Angeles Dodgers, 40-39, in a semifinal for the ages that went three tiebreakers. Guerrero, who in the first round had 29 homers to break the single-round record of 28 by Josh Hamilton at Yankee Stadium in 2008, hit 29 again in the next round.

Pederson ripped 27 homers in regulation and hit two more in the bonus round to tie. Guerrero then hit eight more going first in the 1-minute swing-off but Pederson matched him at 37 on his last.

Each player then had three swings and both homered once. They repeated the tiebreaker and Guerrero smacked two homers while Pederson connected on his first swing but then hit a liner and a grounder to end the epic battle.

"I believe in God and I believe in myself but that's one hell of a player over there," Guerrero said through an interpreter to ESPN in reference to Pederson. "That was a great show we put on."

Pederson was spent after the hitting exhibition.

"Insane, just a lot of excitement. That's why you participate in that," he said to ESPN. "I feel bad he's got to keep hitting. I'm toast."

Guerrero hit 91 homers total to pass Giancarlo Stanton's Derby record 61 set in 2016.

"That was so much fun to watch," Alonso said. "I'm glad I didn't face (Guerrero) in an earlier round. He probably would have knocked me out."

In the other semifinal, Alonso outhomered Ronald Acuna Jr. of Atlanta 20-19.

Guerrero, the son of 2018 Baseball Hall of Fame inductee Vladimir Guerrero, in the first round bettered Oakland's Matt Chapman, who had 13 homers.

Guerrero, 20, was the youngest participant ever. Along with Acuna Jr., 21, they marked the first time multiple players under the age of 22 took part.

In other first-round results, Pederson beat Alex Bregman of Houston 21-16; Acuna won 25-18 over Pittsburgh's Josh Bell, and Alonso hit his 14th homer with one second left to edge Cleveland's Carlos Santana by one to the dismay of the crowd.