Wilson Ramos, one of the bright young stars of the Washington Nationals, hit a home run Saturday night, one of two solo homers (Danny Espinosa hit the other) that gave his team a 2-1 win over the Cincinnati Reds.

That's the good news. Here's the bad news:

Ramos twisted his right knee while chasing a passed ball in the seventh inning, immediately dropped to the ground and remained there for several minutes. He had to be helped off the field by two trainers, his face contorted into a grimace.

Ramos went for an MRI exam after the game as the Nationals made plans to summon a catcher from their farm system.

While no official roster move had been made as of early Sunday, here's who they've summoned:

The Washington Nationals won't know for sure until Sunday morning just how serious the injury is to catcher Wilson Ramos, but in need of an immediate move to have a backup catcher for Sunday's game, the club is planning to give Sandy Leon an opportunity.

Leon, 23, is a switch-hitting catcher who is considered one of the Nationals' best prospects at the position and was named the best defensive catcher in the Carolina League during the 2011 season by Baseball America. Leon has drawn raves from the Nationals' scouts since he signed in 2007 for his exceptional receiving skills, his quick release and his strong throwing arm.

Ramos is expected to be placed on the DL Sunday; Leon will be added to the Nats' 40-man roster, which currently stands at 39 players.

UPDATE: An early Sunday report indicates Ramos will need knee surgery; it could possibly end his season.

UPDATE: Looks like Ramos' season is indeed over.

Injury Update: Wilson Ramos MRI revealed torn ACL (right knee). He will be placed on the 15-Day DL today.

— Nationals PR (@NationalsPR) May 13, 2012

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