VIERA, Fla. -- Nationals right-hander Nathan Karns had his toughest outing of the spring Friday against the Cardinals, allowing seven runs (one earned) in two-thirds of an inning.

After the game, manager Davey Johnson revealed that Karns has been dealing with a right leg issue, which dates back to March 2 against St. Louis. Johnson said Karns will likely see a doctor on Sunday.

"It's an issue, so we are probably going to have the doctors check him," Johnson said. "It doesn't feel right. He said it was something he has pitched with, but it's not normal for a guy to have to feel something uncomfortable in his right leg when he pushes off."

After missing most of 2012, Ramos feeling good

VIERA, Fla. -- Nationals catcher Wilson Ramos was behind the plate for three innings in a 16-10 loss to the Cardinals on Friday afternoon, catching starter Jordan Zimmermann. Including Friday's action, Ramos is 3-for-7 this spring, and manager Davey Johnson is satisfied with what he has seen from his catcher.

It also helped that Ramos was able to safely slide into third base on Cards starter Shelby Miller's wild pitch on Friday. Sliding was the final obstacle for Ramos before he was able to get into a game.

"I thought it was a good slide. I thought [Ramos] was going to be out by a mile," Johnson said. "I was pleased with how he looked back there. It looked like he caught for six innings in that one inning."

Ramos said he is mentally feeling better now that he is catching. Ramos had missed most of last season because of a devastating knee injury suffered against the Reds in May.

"For me, I've been out the game for a long time," Ramos said. "I know everyone says I recovered quickly. To me, it was too long. I'm excited for this moment. I enjoy playing."

Right now, Ramos is focused on his game-calling skills. He wants to be on the same page as his pitchers when he is behind the plate.

"I love when I call the game and the pitcher feels good," Ramos said. "So I concentrate more behind the plate, concentrate on calling the game and being on the same page as the pitcher."

For the rest of Spring Training, Johnson plans to have Ramos and Kurt Suzuki split time.

"I want to give them at-bats, build them up to nine innings," Johnson said. "Suzuki is fine, but with Wilson, I want to see if he could do it."

Rodriguez tosses scoreless inning in spring debut

VIERA, Fla. -- Nationals reliever Henry Rodriguez pitched in his first Spring Training game Friday against the Cardinals. He was expected to pitch to one batter, but retired all three batters he faced in a scoreless sixth inning.

"He went right after them. He hasn't been out there in a while. It's good to have him back," manager Davey Johnson said.

Johnson said all Rodriguez has to do this spring is show he is healthy. Rodriguez missed last year's postseason because of a bone spur in his right elbow. He has dealt with right biceps tightness this spring.

"He has great stuff. He pitched last year with some discomfort," Johnson said. "Before he had the discomfort, he was lights-out. We are going to go in slow with him and make sure he is ready to go."

Mattheus backs Johnson's NLDS decision

VIERA, Fla. -- During the Nationals' 7-5 loss to the Cardinals in Game 5 of the 2012 National League Division Series, manager Davey Johnson decided to use Edwin Jackson --- a starter -- in relief instead of using Ryan Mattheus in the seventh inning with the Nationals leading, 6-3.

Most of the season, Mattheus was used in the late innings and posted a 2.85 ERA. In Game 5, Jackson came in and allowed a run to make it a 6-4 game. But talking to Mattheus about not pitching the seventh inning of that game, he will never second-guess Johnson's decision.

"I would have loved to pitch in that game. There weren't any hard feelings or anything like that," Mattheus said. "That's the manager of our ballclub. He won Manager of the Year. I'm never going to question his decision.

"The night before, Jordan Zimmermann came in and threw a beautiful inning. Why wouldn't you think Edwin Jackson would do the same thing? I just think it didn't work out in our favor. There were no hard feelings, by any means."

In fact, Mattheus credits Johnson for helping him succeed in the big leagues.

"I have the utmost respect for him. He has shown confidence in me since Day 1 when I got here," Mattheus said. 'He has been pivotal in my career. Just as a young player - not necessarily young by age, but young by experience in the big leagues -- in situations, he has handed me the ball. That was a vote of confidence from Day 1. I wouldn't be off to the start I have in my young big league career if it weren't for a manager like Davey Johnson."