However, Betts is the first to manage it while batting leadoff, according to the Elias Sports Bureau. At 23 years old, he also is the second-youngest behind only Harper, who did it at 22.
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Here are some other facts and figures to know about Betts' amazing two-day power binge:
• Betts homered three times in five at-bats on Tuesday, then again in his first two trips to the plate on Wednesday. The five big flies in a span of seven at-bats were the most since the Rangers' Josh Hamilton did it May 7-8, 2012. In terms of Red Sox history, Garciaparra also hit his five homers over a seven at-bat span in '02.
• Betts is the first player in Major League history to homer in both of the first two innings of two straight games, according to Elias.
• The fact that Betts is a leadoff batter makes his power surge all the more impressive. No leadoff hitter had enjoyed a three-homer game since Melvin Upton Jr. for the Rays on Sept. 9, 2012, and none had put together consecutive multi-homer efforts since Alfonso Soriano for the Cubs on May 16-17, 2008. No Red Sox leadoff man had ever homered multiple times in back-to-back contests.
• Betts leads the Majors with 14 homers out of the leadoff spot this season, and his 31 over the past two years is tied for second with the Cardinals' Matt Carpenter, behind only the Mets' Curtis Granderson (35).
• Before May 21, when Betts went deep twice against the Indians, he had two multi-homer games in his career. Less than two weeks later, he now has five.
• Betts is now four homers away from tying the total of 18 he hit in his first full season, when he didn't notch No. 14 until Sept. 9.
• After going deep 15 times in his first 158 career games through last Aug. 21, Betts has done it 22 times in his last 92 games.