VIERA, Fla. -- Nationals right-hander Jordan Zimmermann pitched in a Minor League game against Triple-A Round Rock on Thursday afternoon, throwing five scoreless innings, striking out eight batters and giving up one hit. He threw 58 pitches and 44 of them went for strikes.

The outing was a sharp contrast from Zimmermann's previous start -- on Saturday against the Cardinals -- in which he gave up five runs in two innings. In that outing, Zimmermann was still recovering from the flu and had trouble locating all of his pitches. Against Round Rock, Zimmermann was working fast and pounding the strike zone.

"I felt real good out there," Zimmermann said. "I was locating all of my pitches. My slider was really good today, and the progress in the changeup is really coming along."

After the outing, Zimmermann was working with pitching coach Randy St. Claire on developing his changeup and fixing his mechanics.

"We were working on his changeup," St. Claire said. "That is his fourth pitch, and it's still a work in progress. It's coming along. The more he uses it, the better it's going to get. Out of the stretch, he wasn't getting his hips loaded real good. He was kind of doing a quick slide step where his hips weren't getting loaded. We want to get a little more power and get the lower half [of his body lower]."

Zimmermann still doesn't know where he will pitch to start the season. He is competing against right-handers Collin Balester and Shairon Martis for the fourth and fifth spots in the Washington rotation. If Zimmermann doesn't make the team, he will pitch for Triple-A Syracuse.

"We have almost two weeks left. I'm just going to keep working hard and see what happens," Zimmermann said.

In other news, relievers Joe Beimel and Julian Tavarez are expected to make their Nationals debuts on Saturday against the Astros at Space Coast Stadium. Tavarez will also pitch on Sunday against the Marlins.