JUPITER, Fla. -- Two days ago, manager Frank Robinson said he would try anyone at the leadoff position. Robinson was true to his word on Thursday, inserting Nick Johnson at the top of the batting order. Johnson went 0-for-3 and drove in a run with a sacrifice fly.

Robinson selected Johnson because of his .372 career on-base percentage and the fact that he can steal a base on occasion.

The Nationals have been looking for a leadoff hitter since they demoted center fielder Endy Chavez to Triple-A New Orleans on Tuesday.

The Nationals tried shortstop Cristian Guzman at the top of the order for two games, but he went hitless in seven at-bats and didn't work the count.

"Johnson has a high on-base percentage, and he walks quite a bit," Robinson said. "He hits for a high average, and he gets on base. That's what you need from a leadoff hitter."

Robinson would not commit to Johnson being the Opening Day leadoff hitter, even if he was productive the rest of the exhibition season. Robinson did say that Johnson would be at the top of the lineup on Friday against the Devil Rays.

"I'm really not going to think about the Opening Day lineup until Sunday night after the ballgame (against the Mets)," Robinson said. "I'll see how everybody comes out of it, and I'll see who hits where, especially at the top."

Johnson said he was surprised to see his name at the top of the order. He had never hit leadoff until Thursday.

"I never hit (at the top of the lineup), but we are playing baseball, so I'm going to go out and have fun," Johnson said. "I'm not a speed burner. I'm going to try to get things going for the guys behind me. I try to do that wherever I'm hitting. If the runners are in scoring position, I'll try to drive them in."

The only other hitter capable of being a leadoff hitter is Brad Wilkerson., but Robinson said putting Wilkerson at leadoff is the last resort. He would like to see Wilkerson drive in runs.

Injury report: Outfielder Terrmel Sledge left Thursday's game after five innings because of a strained left calf. He said he felt pain in the second inning while chasing a fly ball.

Sledge insisted that he would not go on the disabled list.

"It's just precautionary. Other than that, I'll be ready for the season," Sledge said.

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Back in action: Third baseman Vinny Castilla played against the Marlins on Thursday afternoon and went 0-for-3 against right-hander Josh Beckett.

It was Castilla's first game since March 18, when he hyperextended his left knee against the Mets.

Castilla said the knee is a little sore, but he is ready for Opening Day.

"I feel good," Castilla said. "Beckett is a great pitcher and he wasn't fooling me with his changeup. I stayed back on it. It's a good sign."

Nice outing: Right-hander John Patterson had his best outing of the spring Thursday, going six innings and giving up three runs against the Marlins. All the runs were scored on home runs by Damian Easley and Juan Encarnacion. Patterson struck out four batters and walked one.

Coming up: The Nationals play their final exhibition home game on Friday afternoon against the Devil Rays. Right-hander Zach Day will start for Washington, while left-hander Mark Hendrickson will get the nod for Tampa Bay.

Day's last appearance was on March 21 against the Marlins, when he pitched five shutout innings in a 1-0 win. He has been affected by rainouts and has pitched in an intrasqaud minor league game.