Harper's achievement came first.
The Washington Nationals were leading the Miami Marlins 1-0 at Nationals Park in Washington, D.C. when the slugger stepped in to face righty Odrisamer Despaigne in the fourth inning. Harper eyed Despaigne's first offering. He sent the 76.3 mph curveball over the right centerfield fence for his 29th home run of the season. His solo shot traveled 402 feet and left the bat at 101.3 mph, according to ESPN's Home Run Tracker.
Harper is the 14th player in Major League Baseball history to hit 150 home runs before his 25th birthday, which occurs in October. The Nationals won Monday's battle 3-2. Harper was 2-for-4 with an RBI in the victory.
"Supreme talent," Nationals first baseman Adam Lind told MLB.com, regarding Harper. "It's been a blessing to watch him. I feel like I've played over the past four or five years with some of the best in the game. As far as talent and his age, he's by far the best."
Trout's feat came in a losing effort.
The ultra-talented Los Angeles Angels outfielder settled in against Baltimore Orioles righty Dylan Bundy in the fourth inning. He took Bundy's first offering, a 90.4 mph four-seam fastball, and belted it to left field. The line drive resulted in a double and hit No. 1,000. He received a standing ovation.
"It felt pretty good," Trout told reporters, according to the Los Angeles Times. "I just wanted to get it over with."
Trout was also 2-for-4 with an RBI in his contest, including a home run in the sixth inning. The Nationals lost 6-2 to the Orioles.
After the game, Trout's teammates gave him a shower with a slushy, baby powder, coffee creamer, cereal, eggs and more.
"Birthday Gift from the boys !! #Angels," Trout wrote on Twitter.
Harper is hitting .327 this season and leads the National League with a .621 on-base percentage and 1.044 OPS. Trout, who turned 26-years-old Monday, is hitting a career-best .346 with 23 home runs. He leads the American League with 12 intentional walks.
"You obviously want to hear your name with the greats and the Hall of Famers when you do something," Trout told MLB.com.
"It makes you feel good. It makes you feel special to be a part of such good company. For me, it's just going out there and playing. I'm not trying to chase any numbers. We're trying to get to the playoffs, and that's the main goal."