In this Sept. 27, 2017, file photo, Arizona Diamondbacks' J.D. Martinez, right, watches the flight of his home run against the San Francisco Giants during the ninth inning of a baseball game in Phoenix. Credit: Ross D. Franklin | AP

The Boston Red Sox reached agreement on a reported five-year, $110 million contract with outfielder/designated hitter J.D. Martinez on Monday — the day of their first full-squad workout of spring training — taking the best power hitter off this slow-developing free agent market and giving the Red Sox a powerful answer to the impressive winter moves of their American League East archrivals, the New York Yankees.

Martinez, 30, hit 45 homers with a major-league-leading .690 slugging percentage in 2017, which he split between the Detroit Tigers and Arizona Diamondbacks. In just 62 games in Arizona, he hit 29 homers, drove in 65 runs and propelled the Diamondbacks into the NL Division Series.

While agent Scott Boras attempted to drum up big-money interest in Martinez elsewhere, reportedly seeking $200 million or more at the outset, it always seemed almost predestined that he would wind up with the Red Sox, who desperately needed his bat to anchor an offense that hit just 168 home runs last season, by far the fewest in the AL.

The contract with Boston reportedly contains two opt-out clauses for Martinez, the first of which comes after just two seasons — giving him the option of retesting free agency at a point when the market may be more robust.

Despite winning back to back AL East titles in 2016 and 2017, the Red Sox fired manager John Farrell and replaced him with rookie skipper Alex Cora, then watched as the Yankees, after coming within a game of making it to the World Series, acquired slugger Giancarlo Stanton from the Miami Marlins in the blockbuster trade of the winter and re-signed veteran starter CC Sabathia.

With the Red Sox prepared to start an outfield of Andrew Benintendi, Jackie Bradley Jr. and Mookie Betts, Martinez could see the bulk of his at-bats in the DH role, which was manned primarily by Hanley Ramirez in 2017. Ramirez, meanwhile, appears destined to platoon at first base with veteran Mitch Moreland.

With Martinez and Eric Hosmer (eight years, $144 million from the San Diego Padres) coming off the board in the past few days, third baseman Mike Moustakas is the best available hitter on the market, while Jake Arrieta heads the list of still-available starting pitchers.

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