Updated

Nationals catcher Wilson Ramos has a torn anterior cruciate ligament in his right knee, the latest major setback for the NL East leaders.

Ramos' knee buckled as he chased a passed ball during the seventh inning of a 2-1 win over the Cincinnati Reds on Saturday night. He fell on his back in pain and had to be helped off the field, putting little weight on the knee.

The Nationals feared that he'd torn the ligament, which was confirmed overnight by an MRI. The young catcher is the 11th Nationals player to go on the disabled list this season and the latest of several major leaguers to tear an ACL this month.

"We're going to have to start eating bananas or something to change our luck," manager Davey Johnson said before a rain-delayed game Sunday. "We've had more than our fair share of key players go down."

The Nationals called up catcher Sandy Leon from Double-A Harrisburg to back up Jesus Flores. The 23-year-old Leon was batting .319 with a homer and 12 RBIs in 27 games at Harrisburg.

It's been a rough seven months for Ramos, who had one of the best seasons by a major league rookie last year. He went home to Venezuela to play winter ball and was abducted at gunpoint in front of his parents' home in Valencia.

Police commandos freed him two days later and arrested suspects who were trying to demand ransom. Ramos got 11/11/11 — the date he was freed — tattooed on his arm.

He tore up his knee Saturday when his spikes caught in the grass as he planted his foot to pick up the ball, forcing his knee to buckle. He fell to the ground in severe pain.

The Nationals have managed to stay in first place in the NL East despite a series of injuries that sapped every part of the team. Third baseman Ryan Zimmerman recently returned from a sore right shoulder that forced him to miss 13 games. Relief pitchers Drew Storen and Brad Lidge, left fielder Mike Morse and utility man Mark DeRosa were among those who went on the disabled list in the opening month.

The past week has been especially tough. Right fielder Jayson Werth had surgery Monday to repair a broken left wrist that's expected to sideline him for at least three months. On Friday night, rookie outfielder Bryce Harper needed 10 stitches to close a gash above his left eye, caused by slamming a bat against a wall near the dugout.

Harper was back in the lineup Saturday. Seven innings later, Ramos got hurt.

There's been a rash of knee injuries in the major leagues already this month.

Yankees closer Mariano Rivera tore the ACL in his right knee while chasing a fly ball during batting practice in Kansas City on May 3. Rivera, baseball's career saves leader, hopes to return next season.

The Brewers lost two infielders to the same injury. First baseman Mat Gamel tore his right ACL while chasing a foul pop on May 1 and hitting the wall at Petco Park in San Diego. Four days later, shortstop Alex Gonzalez tore his right ACL while sliding into second base.