Viera, Fla. ? It’s only an exhibition, and it’s only spring training, when wins and losses don’t count.

Still, for a team that finally is setting down roots, it’s a big deal to play a game — any game — with “Nationals” on the jerseys and a curly “W” on the caps.

After so much time in limbo, the Washington Nationals nee Montreal Expos open the preseason today by playing host to the New York Mets, giving baseball fans in the nation’s capital their first chance to root, root, root for the home team since the Senators left for Texas after the 1971 season.

“It’s going to be a very special day, even though it’s just spring training,” general manager Jim Bowden said Tuesday in his office overlooking the field at Space Coast Stadium, where groundskeepers were mowing grass and raking dirt.

“You normally don’t televise the very first game of spring training,” he added, “but we’re on national television tomorrow because this is a historic moment.”

Braves

At Kissimmee, Fla., the Atlanta Braves completed a $47 million, four-year contract extension with Tim Hudson, locking up a former 20-game winner who could have become a free agent at the end of the season.

“It feels good to get it done,” Hudson said, sitting at his locker before a spring-training workout.

He will make $6.75 million this year. His new deal calls for a $10 million signing bonus, payable when the contract is approved by the commissioner’s office, and salaries of $4 million in 2006, $6 million in 2007 and $13 million each in 2008 and 2009.

Yankees

At Tampa, Fla., the Yankees announced that Randy Johnson would miss his first scheduled spring-training start Thursday because of tightness in his left calf.

The problem is not considered serious, and the left-hander is expected to be ready for what would have been his second start Tuesday.

Marlins

At Jupiter, Fla., while Dontrelle Willis got limber, the guys facing him brought the lumber — or aluminum, in this case. The Florida lefty was hit hard in his spring debut Tuesday, with the University of Miami zinging him with metal bats. Willis gave up six runs and six hits in 21/3 innings, and the college boys won 9-7 in an exhibition at Jupiter, Fla.

Astros

At Kissimmee, Fla., another prominent lefty got in some work. Andy Pettitte faced hitters for the first time since season-ending elbow surgery in August, pitching a shaky inning in Houston’s intrasquad game.

Pettitte threw only fastballs during his 28-pitch performance, a cautionary measure to prevent a setback in his recovery. He gave up two runs, two walks and three hits before getting an out.

Pettitte stayed in to record four outs in the inning because the Astros wanted him to get in some extra work.

“I felt like I hadn’t pitched in a long time,” Pettitte said. “I didn’t feel real comfortable out there today.”

Pirates

At Bradenton, Fla., the Pittsburgh Pirates opened exhibition play by beating Valparaiso, 12-0. Josh Fogg pitched two scoreless innings, and non-roster infielder Jose Leon homered and drove in three runs.