CLEVELAND -- The Guardians are losing their extraordinary leadoff hitter and adding one with power and potential.

Cleveland placed outfielder Steven Kwan, who leads the AL with a .353 average, on the 10-day injured list Monday with a strained hamstring he sustained while running down a fly ball over the weekend.

Kwan felt tightness in his hamstring and was pulled from Saturday's win over the Angels as a precaution. An MRI revealed an acute strain and the Guardians said Kwan likely will be out for up to one month.

Kwan said he had hamstring issues while playing at Oregon State and in the minors.

His injury is a blow to the AL Central-leading Guardians, but it's giving the team a chance to promote hard-hitting prospect Kyle Manzardo, who has been bashing minor league pitchers this season and will now join a Cleveland lineup that can use some middle muscle.

The Guardians have been one of the season's early surprise teams -- they're 22-12 heading into their series opener against Detroit -- with Kwan a big reason for the club's fast start.

He seems to start or be in the middle of virtually every rally, and the 26-year-old continues to be one of the league's best defensive outfielders. Last year, he won his second straight Gold Glove.

Manzardo's reputation as a slugger preceded his arrival in Cleveland.

The 23-year-old was acquired at last year's trade deadline from Tampa Bay for pitcher Aaron Civale. The Rays were reluctant to part with Manzardo but they needed pitching while the Guardians have been craving a big bat in the middle of their order.

Manzardo had a strong spring for the Guardians, who had him start the season at Triple-A Columbus to build confidence. He's done just that, hitting .303 with nine homers, 10 doubles and 20 RBI in 29 games.

Cleveland fans have been clamoring for Manzardo, who will likely play some first base and be used as a DH by first-year manager Stephen Vogt.

Also, the Guardians activated left-hander Sam Hentges from the injured list. The reliever has been out since training camp with a middle finger issue.