Turner suffered a non-displaced fracture on his right index finger Tuesday in the bottom of the first inning of a much-anticipated game against the Philadelphia Phillies that was billed as Harper's homecoming. Wednesday morning, the Nationals placed Turner on the 10-day injured list.
The injury occurred with one out and nobody on, when Turner tried to bunt on an 0-1 offering from Phillies starter Zach Eflin. Eflin's 92 mph fastball hit Turner on his finger, causing him to fall back onto the ground.
Manager Dave Martinez said there is no timetable yet for Turner's return.
"It's a big loss," Martinez said. "He's our starting shortstop. But we've got to keep going."
Although it was unclear whether the ball hit Turner's bat in addition to his finger, the pitch was ruled a foul-ball strike by plate umpire Paul Emmel.
After being tended to by the team's medical staff, Turner walked into the dugout under his own power. He was replaced by utility man Wilmer Difo, who completed the at-bat by striking out against Eflin.
"Doesn't matter if it's the first game or the last game of the year, injuries aren't fun," Turner said. "Takes you out of the lineup, takes you out of the game, and you just want to be out there competing. Not fun, but it is what it is."
It's not the first time that Turner has sustained an injury after being struck by a pitch. In June 2017, he suffered a broken wrist when he was hit by a fastball from Cubs reliever Pedro Strop. Turner missed two months as a result of the injury.
"Anytime you lose your starting shortstop for an extended period of time, especially a player as talented as Trea, it's just tough to swallow," first baseman Ryan Zimmerman said. "But the season doesn't stop for anybody, so just got to keep going."
A former first-round pick of the San Diego Padres, Turner was acquired by Washington in a 2015 trade. The following year, he hit .342 and stole 33 bases in 73 games, and finished second in National League Rookie of the Year voting.
Turner was off to a fast start this season, going 5-for-13 with two homers and four stolen bases over the Nats' first three games. His three steals on Opening Day tied a major league record. He went deep twice against the Mets on Sunday, including a walk-off homer that gave Washington a 6-5 win.
First baseman Matt Adams also exited Tuesday's game early, after he fell over a railing trying to catch a foul pop in the top of the first inning. The Nats said Adams was removed because of back spasms. He was replaced by pinch-hitter Zimmerman in the bottom of the fourth.
Washington has already been hit hard by injuries, losing veteran utility man Howie Kendrick (hamstring) and outfielder Michael A. Taylor (hip, knee) during spring training. If Turner misses extended time, Difo would probably take over as the starting shortstop.
To replace Turner on the 25-man roster, the Nationals recalled infielder Adrian Sanchez from Triple-A Fresno. With Washington's new top minor league affiliate based on the other side of the country, Sanchez left Tuesday evening, flew from California to Chicago, caught a connection, and landed in Washington on Wednesday morning.
The Nationals plan to activate utility player Kendrick off the IL on Thursday, when Washington opens a three-game series against the Mets in New York.
The Associated Press contributed to this report.