Manager Don Mattingly compared the severity of Hernandez's hamstring injury to Yasiel Puig's and Howie Kendrick's. Kendrick has been on the disabled list for three weeks and still can't run at full speed.
With Hernandez unavailable, Joc Pederson was back in center field for the opening game of the Dodgers' three-game home series against the San Francisco Giants. Hernandez, who is batting .308, recently replaced the slumping Pederson as the team's primary center fielder.
Mattingly said rookie Jose Peraza could also start some games in center field while Hernandez is sidelined. Primarily a middle infielder, Peraza played 17 games in center field in the minor leagues.
Peraza was acquired from the Atlanta Braves leading up to the July 31 non-waiver trade deadline.
Hernandez was replaced on the active roster by catcher Austin Barnes, who was promoted from triple-A Oklahoma City. Earlier in the day, Barnes was named to the Pacific Coast League's all-league team.
Late Monday, the Dodgers acquired triple-A outfielder Justin Ruggiano from the Seattle Mariners in exchange for a player to be named or cash considerations.
No-hit by Jake Arrieta of the Chicago Cubs on Sunday, the Dodgers became only the second team in major league history to be no-hit twice in a 10-day window.
Carl Crawford was part of a Tampa Bay Rays team that was no-hit twice in 2010, but reached the postseason.
The last two Dodgers teams to win the World Series were no-hit victims.
In 1988, Tom Browning of the Cincinnati Reds threw a perfect game against them.
In 1981, Nolan Ryan of the Houston Astros no-hit them.
Upcoming roster moves
Barnes' promotion was a day earlier than expected, as it looked as if he would be recalled Tuesday, when teams are permitted to expand their rosters to as many as 40 players.
Right-hander Joel Peralta, who is on the disabled list because of a strained neck, was at the stadium Monday and will be activated.
The team also prepared lockers for right-hander Mike Bolsinger and left-hander Ian Thomas.
Mattingly wouldn't say whether the Dodgers plan to call up top prospects Corey Seager and Julio Urias this month.
Of the two players, Seager is more likely to be promoted to the major leagues. The 21-year-old shortstop spent the majority of this season at triple A.
Urias, a 19-year-old left-hander, pitched in triple A for the first time Monday night. He pitched an inning and was charged with three runs, two hits and four walks.
Urias was one of three double-A pitchers promoted to triple A in recent weeks, along with Jharel Cotton and Chris Anderson. Cotton started the season in low-A Great Lakes.