Stephen Strasburg, taking two steps up in the minors to pitch for Class AAA Syracuse, was perfect through five innings before allowing two singles to start the sixth. (Nicholas Lisi/Associated Press)

Pitching for the Class AAA Syracuse Chiefs on Saturday night in the fifth start of his minor league rehabilitation assignment, Strasburg, 23, breezed through five perfect innings against the visiting Rochester Red Wings before a pair of singles to open the sixth inning ended his night after 64 pitches. Prior to Saturday night, he had not thrown more than three innings or 60 pitches in any rehab start, nor faced any competition above Class A.

“I’ll let the numbers do the talking,” Strasburg said, when asked how his elbow felt. “It felt great.”

Strasburg’s final pitching line – five innings, two hits, one earned run, no walks, seven strikeouts – only hints at his dominance in front of 9,678 (well short of a sell-out) at Alliance Stadium. Facing a veteran lineup that included three hitters with big league experience and no one younger than 26, Strasburg collected seven groundball outs (vs. only one in the air). Entering the sixth, he had allowed only one ball to leave in the infield. All seven of his strikeouts were of the swinging variety – the majority of them coming against his off-speed pitches. In previous starts, he had struggled at times with command of those pitches.

Facing Class AAA hitters, he said, “is a better test — to see how your stuff compares. These guys, a lot of them have been up and down in the big leagues. Their approach is probably the closest to actually pitching in the big leagues. It’s good to go out there, setting up guys and pounding the zone with pitches and using them effectively.”

Although Strasburg’s fastball topped out at 98 mph Saturday night, he relied more heavily on a sinking two-seamer, at 92-95 mph, in order to induce groundballs and pitch more efficiently. He needed only nine pitches to navigate the third inning, nine more in the fourth and eight in the fifth.

After the fifth inning, with Strasburg already at 58 pitches, television cameras from the local broadcast caught Chiefs pitching coach Greg Booker having a conversation with Strasburg in the dugout. Strasburg soon went back out for the sixth, but back-to-back singles by Aaron Bates and Steve Holm ended his night. The Bates at-bat marked the first time all night Strasburg fell behind 2-0 in the count.

“This is my fifth start in [the span of] a year,” Strasburg said. “So I’m still probably in the middle of spring training mode, and it’s probably going to feel that way, unfortunately, until the end of the year.”

Cumulatively, Strasburg has thrown 14 1/3 innings on his rehab assignment, and has allowed 13 hits and eight earned runs (giving him a 5.02 ERA), with 25 strikeouts against only three walks.

Although the Nationals have not revealed a specific timetable for Strasburg’s return to the majors, it is believed he will make another minor league start on Sept. 1 – most likely for Class AA Harrisburg, the only Nationals affiliate with a home game that day – then possibly make his season debut at Nationals Park as soon as Sept. 6.