CLEARWATER, Fla. -- A perfect storm could be brewing for the Pirates' starting rotation.

The opening foursome is approaching the regular season in lights-out mode, and the two in the wings are also taking flight.

Pitching in nearby Dunedin against Toronto's Triple-A team to shy him away from the Phillies -- whom he'll face in the season's second game on April 7 -- Jeff Karstens pitched shutout ball for 7 1/3 innings, allowing three hits and punching out 10.

"Everything went very well for him," said manager Clint Hurdle, citing eyewitness reports.

Karsten's effort followed James McDonald's seven innings of two-hit ball on Saturday against Houston and Erik Bedard's effort on Monday against the Orioles, whom he blanked for 5 2/3 innings on one hit before tiring.

Meanwhile, two stand-by right-handers are casting growing shadows.

On Tuesday, A.J. Burnett took another step forward -- the only direction in which he has been heading since returning to camp on March 10, eight days after his eye surgery -- by throwing two innings and 48 pitches in a simulated game under the watchful eyes of pitching coach Ray Searage.

"Ray was very encouraged by the outing," Hurdle said. "A.J. was very good and efficient. His breaking ball and off-speed came into play better in the second inning."

Burnett is next due to go three innings in a Minor League game on Sunday, and beginning competitive pitching will be a sure sign of getting close.

On Wednesday, Charlie Morton starts against the Rays, looking to build on the four shutout innings he threw at Detroit on Friday.

So the two right-handers are on nearly identical throwing schedules, putting them on parallel paths into joining the rotation.

Pirates' Alvarez ends skid with single off Lee

CLEARWATER, Fla. -- Old baseball expression: The baseball will find anyone playing a strange position.

New Pirates expression: The microscope will find Pedro Alvarez.

The conspicuous third baseman snapped his hitless drought, and against a worthy foe, with a sharp single to left-center off Cliff Lee in the fifth inning of the Pirates' 5-4 loss Tuesday.

That hit was his first in 19 at-bats, and only a temporary interruption of his trying spring. Alvarez fanned on his three other at-bats, giving him 13 whiffs in his last 22 at-bats.

That included taking a third strike from Michael Stutes for the third out in the eighth after four consecutive hits had rallied the Pirates into a 4-4 tie.

Sure, there are no everyday players in Spring Training, and Alvarez also took one weekend off with a tender left knee. Still, it is astonishing the hit was his first in two weeks, since a single on March 14 against the Orioles.

Worth noting

• Yamaico Navarro had to leave the game after taking a seventh-inning Kyle Kendrick pitch on his left forearm and was sent to have X-rays taken even before the game's end.

• A sure sign of regular season's approach is seeing closers pitch on consecutive days, and Joel Hanrahan did so for the first time Tuesday. He fired one hitless inning against the Phillies after having worked an inning in a Pirate City camp game on Monday.

• Josh Harrison, playing shortstop, kept the game tied at 4 on Tuesday with a run-saving play to end the eighth, gloving John Mayberry's hard grounder up the middle with the go-ahead run on second, and throwing on the run to nail him.

• Major props to Kirk Singer (no relation), the skinny (6-foot-2, 163 pounds) 22-year-old second baseman who joined the travel squad from Minor League camp and singled for the tying run in the eighth then stole second, and also flawlessly handled three chances in the field.