During the 2017 season, Scooter Gennett and J.D. Martinez went deep four times in a game, becoming just the 17th and 18th players in Major League Baseball history to accomplish the feat.  
:: RARE FEATS ::
To put into perspective how rare it is for a hitter to homer four times in a game, it happened just once each in the decades of the 1960s, '70s, 80s and '90s.
And after Ed Delahanty became the second big leaguer to accomplish the feat on July 13, 1896, no one did it again until Lou Gehrig nearly 36 years later on June 3, 1932.
"[In my last] at-bat, I came up and I was like, 'Just go up here and try to have a good at-bat," Martinez said. "'Just keep doing what you've been doing all day.'
"'You know what, if it's meant to be, it's meant to be. It's going to happen. There's no point in trying to force it. Just go up there and have a good at-bat.'"
Barry Bonds, Hank Aaron, Babe Ruth and Alex Rodriguez -- the Big 4 on MLB's career homer list -- never hit four in a game. Here are the 18 who did:
• J.D. Martinez, D-backs, Sept. 4, 2017

• Scooter Gennett, Reds, June 6, 2017

• Josh Hamilton, Rangers, May 8, 2012

• Carlos Delgado, Blue Jays, Sept. 25, 2003

• Shawn Green, Dodgers, May 23, 2002

• Mike Cameron, Mariners, May 2, 2002

• Mark Whiten, Cardinals, Sept. 7, 1993

• Bob Horner, Braves, July 6, 1986

• Mike Schmidt, Phillies, April 17, 1976

• Willie Mays, Giants, April 30, 1961

• Rocky Colavito, Indians, June 10, 1959
• Joe Adcock, Braves, July 31, 1954
• Gil Hodges, Dodgers, Aug. 31, 1950
• Pat Seerey, White Sox, July 18, 1948
• Chuck Klein, Phillies, July 10, 1936
• Lou Gehrig, Yankees, June 3, 1932
• Ed Delahanty, Phillies, July 13, 1896
• Bobby Lowe, Beaneaters, May 30, 1894