The scoreboard disagreed, but Jhoulys Chacin felt happy about his first Triple-A rehab start.

The Rockies righthander, making his way back from a shoulder strain, threw 80 pitches over 4 2/3 innings and gave up the first four runs - two of which were unearned - in a 9-0 Sky Sox loss Thursday to Iowa at Security Service Field.

"I felt fine," said the 26-year-old product of the Colorado system, who won 14 games for the Rockies last year. "My ball was moving very well and I was controlling the ball the whole game, just a couple of hitters I got off a little bit. It wasn't a big deal. I threw just one bad pitch to the catcher and that's why he hit that ball. Besides that I felt fine."

That one pitch was laced for a two-run double by the Cubs' Eli Whiteside, also a major-league veteran.

Chacin struck out four, walked one and gave up five hits before being pulled with two outs in the fifth. He threw 52 strikes in his 80 pitches.

Colorado Springs managed just four hits against Iowa starter Tsuyoshi Wada, who threw five scoreless innings and lowered his ERA to 0.68 through four starts.

Two of Chacin's strikeouts came against touted prospect Javy Baez, a shortstop who hit 37 home runs over two levels last year. Baez went 0-for-5.

Chacin averaged 88 mph on his fastballs, working between 86 and 91, which is in line with what he throws at full strength.

"I really don't worry about my velocity," Chacin said. "If my ball is moving and my breaking ball is good, that's what I'm more worried about and if my arm feels fine."

The injury occurred as Chacin began throwing after a winter layoff. He said he was throwing too far from the side during batting practice when the shoulder strain must have occurred. It was then aggravated the more he threw in preparation for the season.

His rehab started with a pair of starts for High Class-A Modesto, where he also went 42/3 innings in his last start.

To go from spring training in Arizona to a pair of games in California left him feeling the difference of working in the high altitude in Colorado Springs.

"Here you're a little bit higher and you get tired a little bit, but I feel fine," he said. "Everything feels fine. Like I said, my arm feels fine. That's the big thing."

Assuming all goes to plan in his recovery from Thursday's start, it seems likely that Chacin will get one more rehab start.

"I just haven't thrown that many innings, so I don't know," Chacin said. "I haven't pitched five innings yet. I don't know what they are going to decide. I feel fine and everything, my arm is feeling good, so I just need to get my innings and throw more pitches."