SEATTLE -- When Major League Baseball rolled out its ¡°Let the Kids Play¡± promotional campaign this year, the Mariners clearly took them seriously, starting seven rookies in Thursday¡¯s 11-5 loss to the Reds at T-Mobile Park.

With those kids come some growing pains, as evidenced by right-hander Justin Dunn, the club¡¯s No. 5 prospect, walking five batters and lasting just two-thirds of an inning in his MLB debut.

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But there also comes youthful energy and untapped potential, which right fielder Kyle Lewis flashed again as the 24-year-old continued his impressive introduction by going 3-for-5 with a double and his third home run in his first three games.

Lewis unleashed a 457-foot blast leading off the fifth inning, the longest Statcast-recorded home run of the season by a Mariner, and joined Trevor Story of the Rockies (2016) as the only players to homer in each of their first three career games in MLB history.

¡°I don¡¯t think about it as crazy,¡± Lewis said. ¡°I just try to play my game, day by day. Things like that are kind of more external. I try to remain internal, if I can, and continue to play my game.¡±

Lewis, the Mariners¡¯ first-round Draft pick in 2016, is now 5-for-11 with three homers, a double and five RBIs since being called up from Double-A Arkansas on Tuesday.

After Lewis homered off a pair of fastballs in his first two games, he saw nothing but curveballs in his first two at-bats Thursday. But the youngster ripped a leadoff double in the second and singled in the third off starter Tyler Mahle, then got a 94 mph fastball from reliever Lucas Sims in the fifth and launched it over the out-of-town scoreboard.

¡°He¡¯s obviously seeing the ball really good and not overthinking,¡± manager Scott Servais said. ¡°The thing that¡¯s stood out for me is he¡¯s in the moment. He¡¯s not looking ahead, he¡¯s not looking behind. He¡¯s just there, playing the game and trusting his ability.

¡°I love to see a young player come to the big leagues like that and get off to the start he has. He looks very comfortable, like he¡¯s been here a long time, which is a great way to look when you¡¯ve got three games under your belt.¡±

Shortstop Donnie Walton recorded his first MLB hit with a second-inning single, utility man Dylan Moore continued his solid season with a two-run homer and fellow rookies Shed Long and Braden Bishop each chipped in with hits as well as the first-year players accounted for eight of Seattle¡¯s 11 hits.

The seven rookie starters, including Dunn on the mound, equaled a franchise record set back in 1983 when Harold Reynolds was one of the newcomers. The Mariners overcame Dunn¡¯s shaky start to take a 5-2 lead into the seventh, but the Reds rallied behind three late homers -- including a Freddy Galvis grand slam -- to avoid a series sweep.

Dunn acknowledged his adrenaline was overflowing when he took the big league mound for the first time. The 23-year-old had just 39 walks with 158 strikeouts in 131 2/3 innings at Arkansas this year, but couldn¡¯t find his command or slow things down in his debut.

¡°There were a lot of jitters. You want to impress, obviously, and show you deserve to be here,¡± Dunn said. ¡°But at some point you have to get past that and fill the zone up.¡±

¡°I thought his stuff was fine, he was just amped up,¡± Servais said. ¡°He¡¯ll learn from it. We¡¯ll give him another shot in five or six days when his turn comes up again and he¡¯ll be much better next time out.¡±