BRADENTON, Fla. -- James Shields' exhibition season has gone as well as he could expect. Except for one pitch.

Shields struck out seven in six innings and allowed his first earned run of spring training as the Tampa Bay Rays beat the Pittsburgh Pirates 2-1 Saturday.

Tampa Bay's scheduled opening-day starter, Shields allowed four hits and walked none. He had thrown 11 consecutive scoreless innings before Andrew McCutchen homered for the first time in the exhibition season, connecting on a fastball in the sixth.

"I was going to go down and away with the fastball," Shields said. "It leaked back over the plate."

Shields threw 46 of 67 pitches for strikes. He had not expected to pitch past the fifth.

"I was ahead in the count," he said. "I was really efficient with my pitches. That's a recipe for success. You get to do that, you get to go deeper into games."

To celebrate St. Patrick's Day, the Rays wore green necklaces, the Pirates wore green hats, and the teams used green bases.

Pittsburgh's Jeff Karstens allowed three hits and three walks, striking out five in five innings.

"He didn't have his best stuff," Pirates manager Clint Hurdle said. "He pitched himself into a couple corners, but he got out of innings."

Karstens, a possible opening-day starter, allowed two runners in both the first and second innings but escaped trouble both times.

"He has really, really solid awareness while he's on the mound of everything that's going on around him," Hurdle said.

Karstens worked with catcher Rod Barajas, signed as a free agent during the offseason.

"To throw to him for the first time today was a tremendous help for me because that alone gave me the confidence that, during the year, I can trust whatever he puts down," Karstens said.

Luke Scott, coming off offseason shoulder surgery, hit his first home of spring training in the fifth off Karstens. Scott went 2 for 3 to raise his batting average to .273.

"Things are starting to feel a little bit better," Scott said. "I'm getting better timing, getting better rhythm."

Carlos Pena tripled off Joel Hanrahan in the sixth, Pena's first hit of spring training and Hanrahan's first hit allowed. Pena scored on a wild pitch.

Pirates reliever Jason Grilli had a strikeout and allowed one hit and one walk in two innings. He has not given up a run in five outings.

Game notes
Pirates RHP A.J. Burnett (orbital bone fracture) threw his first bullpen session since surgery March 2. Burnett threw 30 pitches, all fastballs. ... Rays outfielder B.J. Upton did not play, three days after colliding with teammate Desmond Jennings during a game. Manager Joe Maddon hopes Upton can play Tuesday, either against the Miami Marlins or in a minor league game.