WASHINGTON outfielder Bryce Harper reportedly is going to be sidelined at least until July because of surgery on his left thumb.

ESPN.com says the two-time All-Star will have the operation today.

Nationals spokesman John Dever declined to comment. The team was off yesterday, and plays tonight at Houston.

The Nationals put Harper on the 15-day disabled list Sunday, saying he had a sprained left thumb.

Harper was hurt Friday night on a headfirst slide into third base on a triple against San Diego. He didn't leave the game until after the next inning.

"I slid into the bag and I caught it a little bit," he said about his thumb after that game. "Went into the dugout, swung a couple in the cage, felt fine. Went out to the outfield, it swelled up a little bit . . . So I got in and got some treatment on it."

Harper is hitting .289 with one home run and nine RBI.

The injury came less than a week after Harper was yanked from a game for what manager Matt Williams termed "lack of hustle" after heading toward the dugout instead of running out a groundout.

For the 21-year-old Harper, the 2012 NL Rookie of the Year, this will be the second prolonged injury absence of his brief career.

Last season, he missed 31 games because of bursitis in his left knee after crashing into outfield walls twice. He wound up having an offseason operation on the knee.

He said this winter that he hadn't been 100 percent healthy even before running into walls while playing defense in games on April 30 and May 13 a year ago. Harper finished last season with a .274 batting average, 20 homers and 58 RBI.

Nate McLouth is expected to get extra playing time during Harper's absence. McLouth signed a 2-year, $10.75 million contract with as a free agent this offseason. He is hitting .118 - four hits in 34 at-bats - with one RBI in 2014. He homered Sunday against the Padres while starting in Harper's place.

Harper's injury is only the latest in a string to key players for the Nationals, and he joins two other members of the everyday lineup who also happen to be middle-of-the-order hitters - third baseman Ryan Zimmerman and catcher Wilson Ramos - along with a key offseason addition to their starting rotation - right-hander Doug Fister - on the disabled list.

Noteworthy

* Houston traded righthander Lucas Harrell to Arizona for cash or a player to be named later. Harrell, 28, was designated for assignment on April 16 after opening the season 0-3 with a 9.49 ERA.

* Cincinnati is asking for more information from Major League Baseball about the replay dispute that led to Bryan Price's first ejection as manager. Price was ejected during the first inning of Cincinnati's 1-0 loss in 10 innings at Atlanta on Sunday. Price asked for a replay after B.J. Upton was called safe at first base on Johnny Cueto's pickoff throw. First baseman Joey Votto caught the ball and swiped at Upton's hand before it touched the base.

The replay was deemed inconclusive and the call stood. Price came out to discuss it and was ejected automatically. The Reds sought clarification from MLB yesterday about why the replay was deemed inconclusive. Price thought that the replay definitively showed that Upton was out.

* St. Louis demoted struggling rookie second baseman Kolten Wong to Triple A along with reserve outfielder Shane Robinson.

* At Cincinnati, the Cubs-Reds game was postponed by rain. No makeup date was announced.

In AL games

* At Arlington, Texas, Sonny Gray (4-1) threw a three-hitter for his first career complete game and the Oakland Athletics beat Texas, 4-0, in Rangers ace Yu Darvish's shortest outing in the major leagues: 3 1/3 innings. Josh Donaldson had a two-run single in the third, and the A's made it 4-0 an inning later when Josh Reddick had an RBI triple before coming home on Daric Barton's sacrifice fly.

* At Chicago, Alejandro De Aza hit a two-run homer and Adam Eaton and Marcus Semien had two-run doubles, leading the White Sox to a 7-3 victory over the Tampa Bay Rays. White Sox rookie slugger Jose Abreu drove in his 32nd run.