The Los Angeles Dodgers’ difficult April got a lot worse Monday with news that two-time All-Star shortstop and 2016 NL Rookie of the Year Corey Seager will undergo season-ending Tommy John surgery.

Dodgers manager Dave Roberts said the operation will be performed Friday in Los Angeles to repair a right ulnar collateral ligament sprain.

“It’s a big blow,” Roberts said.

The 24-year-old infielder had been bothered by a sore elbow since the middle of last season but had tried to deal with the problem with rest and rehabilitation rather than surgery.

Rookie impresses

Pirates rookie Nick Kingham’s nearly perfect debut has earned him at least one more start in the majors.

Kingham took a perfect game into the seventh inning of his first big league start, retiring the first 20 batters in Pittsburgh’s 5-0 win over the St. Louis Cardinals on Sunday.

He left after seven innings, allowing one hit on 98 pitches, in the best debut by a major league starter in more than a half-century.

Now he’s slated to pitch again on Friday at Milwaukee.

On Rangers DL

Texas Rangers left-handed starter Martin Perez was placed on the 10-day disabled list because of right elbow discomfort. The Rangers made the move before Monday night’s series opener at Cleveland. Reliever Jose Leclerc was recalled from Triple-A Round Rock for his third big league stint this season.

LeMahieu has strain

The Colorado Rockies placed second baseman DJ LeMahieu on the 10-day disabled list with a right hamstring strain and activated outfielder Carlos Gonzalez from the DL.

The 29-year-old LeMahieu, a two-time All-Star, is batting .290 with five homers and 12 RBI in 27 games.

Arano on DL

Philadelphia placed right-handed reliever Víctor Arano on the 10-day disabled list because of a mild right rotator cuff strain. The move was made after Arano underwent an MRI and before the Phillies opened a series at Miami.