Yoenis Cespedes of the Oakland Athletics bats during the home run derby in Minneapolis on Monday (US time). Photo: AFP

Oakland Athletics slugger Yoenis Cespedes defended his home run derby title in dominating style on Monday (US time), joining Ken Griffey Jr as the only players to win back-to-back crowns.

The 28-year-old Cuban crushed Cincinnati Reds infielder Todd ­Frazier 9-1 in the final round at Target Field stadium, the home of Major League Baseball's (MLB) Minnesota Twins.

"I just discovered recently Ken Griffey Jr was the only other player to win consecutive titles and it was something that I wanted to accomplish," Cespedes said through an interpreter. "I was able to get past the first round which allowed me to breathe and regather myself and that ­allowed me to win this title one more time."

Former Seattle Mariner Griffey  Jr won the home run hitting ­contest in 1998 and then repeated in 1999.

Cespedes, who hit a total of 30 home runs, led off the final round of the annual long ball showcase, which was delayed one hour at the start because of rain. The former Cuban national baseball team member finished two homers shy of his total in 2013.

His power display included a home run that sailed 452 feet (138 meters) into the outfield seats.

Cespedes stepped up to the plate in the final round after hitting 21 homers in the opening rounds.

He became the fifth consecutive American League player to win the derby. Prince Fielder was the last National League player to take the title in 2009.

Oakland third-base coach Mike ­Gallego, who also threw to ­Cespedes last year at New York's Citi Field, pitched the home run balls.

Frazier had his brother Charlie pitch to him. Charlie Frazier was a sixth-round draft pick but never made it to the major leagues.

This year's event included a change in the format and an ­expanded field of compe­titors.

Some of the game's best sluggers decided to skip the event. Mike Trout, Edwin Encarnacion, Jose Abreu, David Ortiz and Miguel Cabrera decided not to take part for a variety of reasons.

Of the three players who have hit the longest home runs in the league this season, Miami Marlins' Giancarlo Stanton was the only one to compete on Monday night. Stanton blasted a 484-foot homer on April 4.

Trout hit the longest homer of the season so far, a 486-foot monster shot on June 27.

There was still plenty of pop in the event. With the ­revised format, MLB aimed to cut the number of swings each ­batter took in early rounds by reducing the number of outs from 10 to seven, which meant less wear and tear on the two finalists.