Brandon Lowe of the Rays remains atop MLB.com's second American League Rookie of the Year poll, but a familiar name -- Blue Jays third baseman Vladimir Guerrero Jr. -- has emerged as his most serious competitor.

Meanwhile, Mets first baseman Pete Alonso, who was second in the first National League poll, has taken over the top spot. However, he too appears to have a serious competitor, in Braves right-hander Mike Soroka.

Guerrero's ascent has been fast. He began the season in the Minor Leagues as MLB Pipeline's No. 1 prospect. He made his debut in Toronto's 26th game of the season and batted .146 in his first 11 games. About the time some began to wonder if he needed to return to the Minors, Guerrero took off.

He wasn't in the top five in the first Rookie of the Year poll, but slid solidly into second place in this one. Lowe has plenty going for him, too, as a key part of a team that has been one of the best in baseball since Opening Day.

Alonso was second in the first NL Rookie of the Year poll, trailing Padres pitcher Chris Paddack. But after hitting nine home runs in March/April and 10 more in May, Alonso has front-runner status.

Soroka jumped from fourth to second in this poll with a string of solid starts that should move him into the NL Cy Young Award conversation.

These polls were reached by asking 40 MLB.com reporters to vote for their top three choices in each league, with five points for a first-place vote, three points for second and one point for third.

American League
Brandon Lowe, Rays 2B (26 first-place votes)
He's a huge reason the Rays are fighting for the AL East division championship. His two homers Sunday went 455 and 435 feet, and his 14 for the season are already among the most by a Tampa Bay rookie. Lowe's power surge may be a surprise, but overall, he has been pretty much the player the Rays projected him to be after watching him for 43 Major League games last season. He is second among all rookies in home runs and extra-base hits. His two errors are the fewest among MLB second basemen who've played at least 50 games.

Vladimir Guerrero Jr., Blue Jays 3B (12 first-place votes)
He was widely considered one of the best hitting prospects in recent seasons, and he has been as good as advertised. That's not an easy thing to do when his standing as MLB Pipeline's No. 1 prospect is taken into account. Since his slow start, Guerrero has a .915 OPS along with five doubles and seven home runs in his past 25 games.

John Means, Orioles LHP (two first-place votes)
This Orioles season is about identifying building blocks for the future, and this former 11th-round Draft pick projects as a prominent one. The 26-year-old lefty is right out of the mold of O's icons Scott McGregor and Mike Flanagan, with average velocity and a killer changeup. Means has allowed one run or none in six of his 10 starts, and among pitchers who've worked at least 60 innings, his 2.67 ERA is the sixth lowest in the AL. Among rookies, he is second in opponents' batting average (.220) and sixth in strikeouts (50).

Others receiving votes: Michael Chavis, Spencer Turnbull, Ty Buttrey, Marcus Walden

National League
Pete Alonso, Mets 1B (28 first-place votes)
He has cooled off a bit after a blazing two months in which he almost lapped the field. His 21 home runs are eight more than any other MLB rookie, and his 46 RBIs are 18 more than any other NL rookie. He has the most home runs for a Mets rookie before the All-Star break, shattering Ron Swoboda's mark of 15 in 1965. Alonso has seven go-ahead homers, two game-tying homers, 14 go-ahead RBIs and five game-winning RBIs.

Mike Soroka, Braves RHP (12 first-place votes)
He has pitched himself into NL Cy Young contention with a 1.38 ERA that's the second lowest in the Majors. Soroka is the third MLB starter since 1920 to have nine straight starts of one earned run or none, and the first Braves pitcher to do it. For his brief career, he has allowed no more than one earned run in 12 of 15 starts.

Chris Paddack, Padres RHP (no first-place votes)
The Padres have found their ace in this 23-year-old Texan. He was roughed up a bit in his past two starts, but his numbers could hardly be more solid. He didn't allow more than three earned runs in any of his first nine starts, and he's throwing first-pitch strikes 73.4 percent of the time.

Other receiving votes: Austin Riley, Bryan Reynolds, Alex Verdugo, Nick Senzel, Fernando Tatis Jr.