ROUND ROCK -- After turning in a quality start and earning a win for Triple-A Round Rock Sunday, Roy Oswalt believes he's ready to return to the big leagues.

Oswalt threw 100 pitches, 70 of them strikes, over six innings, allowing two runs on six hits while striking out five and walking one in a 4-2 Express victory. The outing was an improvement from his last start, when he threw 85 pitches and lasted only 3 1/3 innings, giving up three third-inning runs with Double-A Frisco on Tuesday.

When asked if he felt prepared to pitch in the Major Leagues again, Oswalt did not hesitate.

"I do," Oswalt said. "I probably could have thrown two more innings. My arm strength's there. The pitch location is getting better. Hopefully the next stop is Arlington."

The Rangers have their rotation set for their three-game series against the Padres that begins Monday. They have yet to name a starter past their off-day Thursday, but Oswalt is a candidate to make his Rangers debut in Friday's series opener against the Rockies in Arlington.

"It's their decision. I can't just go up there on my own," Oswalt said. "I feel like I'm ready. The plan was six starts but, after tonight, I feel pretty well. Everything's coming out of my hand pretty well. The ball's kind of jumping on guys. That's what I was looking for."

In his first three Minor League starts, Oswalt was 0-1 with a 7.50 ERA, striking out five and walking two over six innings while opposing batters hit .341 off him. But Oswalt was much sharper in the six innings he tossed Sunday, citing an improved curveball and a productive bullpen session Thursday with Rangers pitching coach Mike Maddux and his brother, Greg, a four-time Cy Young winner.

"Once you get your fastball location down, your other pitches get that much better," Oswalt said. "Tonight, I was able to throw a lot of balls down in the zone. The last two starts, the ball was elevated a little bit. It worked out tonight."

Oswalt struck out two batters in the first inning and got out of the second unscathed before allowing his first run in the third. He issued a two-out walk to Jimmy Paredes, who stole second base during Scott Moore's 14-pitch at-bat. Moore got the better of Oswalt, fouling off six two-strike pitches before giving Oklahoma City a 1-0 lead with an RBI single.

"That one at-bat kind of messed me up," Oswalt said. "You take 10 of those away and you're in the seventh inning. Once I got to that eighth pitch, I was going to try to throw every pitch I had for strikes and see if I could do it. Every pitch I had for strikes, he kept fouling them off."

Round Rock took the lead with a pair of runs in the bottom of the third, but Oswalt left the game with the score tied at 2. With two outs in the sixth, Angel Sanchez drove home Mike Hessman with the last of his three singles off Oswalt in as many at-bats.

Oswalt threw exactly as many pitches as he planned on throwing in his fourth Minor League start. He threw 30 of his 100 pitches in the third inning, which marked the third straight start he surrendered a run in the third. But Oswalt needed only five pitches to retire the side in the fifth inning, allowing him to throw one more.

"TC [Express pitching coach Terry Clark] came down and said, 'What about a four-pitch inning?' and I think I got a five-pitch one," Oswalt recalled. "I felt strong. It seemed like I threw all my offspeed pitches better this time than I did in my last start. I was kind of struggling with my curveball and changeup. Tonight, I felt pretty well."

Greg Miclat, who led the third inning off with his first home run of the season, hit a two-run bloop double past a diving Brandon Barnes in center field. That gave Round Rock a two-run lead and put Oswalt in line for the win. Neal Cotts and Aaron Heliman combined to throw three scoreless innings to preserve the victory.

"I feel like, after tonight, I can go back to throwing 120-125 pitches and get deep into the ballgame," Oswalt said. "I don't know what the plan is. I know they have a day off Thursday. They'll probably call me and tell me the rotation."