While Cubs ace Kerry Wood headed back to Chicago for tests on his right shoulder, teammate Mark Prior made his first start of spring training.

The news was only good for Cincinnati and St. Louis as Ken Griffey Jr. and Larry Walker took their first swings of the year.

Wood returned Thursday to Chicago to have his pitching shoulder examined. A day earlier, he had to cut short his start after feeling tightness. Wood had an MRI before returning home.

“He’s such a valuable commodity,” Cubs manager Dusty Baker said.

Wood missed two months last season because of tendinitis in his right triceps. He was sidelined for the 1999 season after elbow ligament replacement surgery.

“After what happened last year, this is just precautionary,” Baker said. “It was just a matter of him going back and seeing our team doctor. Right now, it’s nothing. We just decided to do this for a precautionary sake.”

Prior, slated to be the Cubs’ No. 2 starter behind Wood, gave up a run and four hits in three innings for the Cubs in a 5-3 victory over the Seattle Mariners on Thursday.

At Sarasota, Fla., Griffey hit a sharp liner directly into first baseman Carlos Pena’s glove in his first at-bat of the year.

“I said to him, ‘I haven’t had a base hit since July, you could’ve let that one go by,'” Griffey said.

Actually, Griffey’s last hit was Aug. 4, and his final game of 2004 was two days later. At Jupiter, Fla., Walker was hitless in two at-bats and played four innings in the Cardinals’ 4-2 victory over the Houston Astros.

Pirates 1, Braves 0

At Kissimmee, Fla., John Thomson pitched three scoreless innings, and Horacio Ramirez added two more for the Braves.

Indians (ss) 3, Nationals (ss) 1

At Winter Haven, Fla., Aaron Boone hit his first homer since Game 7 of the 2003 American League championship series.

Marlins 5, Nationals (ss) 3

At Viera, Fla., Dontrelle Willis pitched two-hit ball over four innings for Florida.

Rockies 11, Padres 5

At Tucson, Ariz., Todd Helton homered and had three RBIs, and Jason Jennings gave up a hit and a run in three innings for Colorado.

Angels 6, Athletics 5

At Tempe, Ariz., Barry Zito allowed two hits in four innings for Oakland, but prospect Jeff Mathis homered and drove in the winning run with a single to lift the Angels.

Phillies 6, Twins 3

At Fort Myers, Fla., Jimmy Rollins had a bunt single and a three-run homer off Brad Radke.

Orioles 8, Mets 2

At Fort Lauderdale, Fla., Carlos Beltran lost two balls in the sun, resulting in a double by Javy Lopez and a triple by David Newhan.

Indians (ss) 12, Devil Rays 2

At St. Petersburg, Fla., Denny Neagle gave up four runs and six hits in one inning.

White Sox 7, Rangers 2

At Surprise, Ariz., Ricardo Rodriguez, whose right elbow was shattered by a line drive in July, gave up five runs and seven hits in 31/3 innings in his second spring start for Texas.

Giants 7, Diamondbacks 2

At Tucson, Ariz., Jason Ellison’s grand slam capped San Francisco’s five-run ninth inning.

Yankees 8, Blue Jays 0

At Tampa, Fla., Mike Mussina and Carl Pavano each threw three scoreless innings.