CINCINNATI -- There's little doubt that Sam LeCure will be wondering whether his next time on the mound will be for the Reds or Triple-A Louisville.

You can't envy that uncertain feeling, or the tasks LeCure has been handed in his last two starts. For his previous outing last Wednesday, he held his own vs. the Cardinals and lost to ace Chris Carpenter.

On Tuesday, LeCure allowed one run over six innings only to be outdone by Matt Cain's seven-hit shutout for a 3-0 Reds loss to the Giants. The Reds have dropped the first two games of the four-game series.

"That's two tough assignments in a row for Sam," Reds manager Dusty Baker said.

The one run LeCure gave up to San Francisco was a long one -- Juan Uribe's 433-foot home run to left field in the top of the fourth inning. LeCure also allowed five hits and four walks while striking out three. He reached 101 pitches after the sixth and the rookie's career high was 105 for Louisville.

"Their kid pitched great. He did a nice job," Giants manager Bruce Bochy said.

LeCure admitted that having Cain and Carpenter as his opposition got into his head some.

"I didn't want to make a mistake because I knew it could be the difference in the game," LeCure said.

Through three starts since replacing the injured Homer Bailey in the rotation, LeCure is 1-2 with a 3.12 ERA. In his 17 1/3 innings, he's allowed 17 hits and 12 walks with 12 strikeouts.

"We couldn't ask for any more than what he's done," Baker said. "He's thrown the ball well. He's thrown strikes. He's gotten ahead of hitters for the most part."

Bailey, who was on the disabled list with right shoulder inflammation, was eligible to be activated Tuesday but was instead sent to Louisville to make a rehab start. He pitched 4 1/3 innings and allowed five earned runs and six hits vs. Syracuse while throwing 86 pitches. In nine starts for the Reds this season, he is 1-2 with a 5.51 ERA.

Baker and general manager Walt Jocketty have a decision to make for Sunday when the same spot in the rotation comes up -- Bailey or LeCure?

"It remains to be seen. We have to check that out," Baker said. "It's a little too early right now after this loss to come up with that kind of answer."

LeCure benefited from some superb defense behind him. Third baseman Scott Rolen and left fielder Laynce Nix made nice plays in the first inning. After a pair of one-out walks in the third, second baseman Brandon Phillips made a nice stop to his right on Pablo Sandoval's hard grounder to start an inning-ending double play.

"Each time out, I'm becoming a little bit more aware of what it's going to take for me to be successful," LeCure said. "I pitched out of some trouble and did, by my own fault, walk guys and get high in the pitch count. But I did make some pitches, got some double-play balls and got some outs in big spots."

As good as the defense was, the Reds offense could do nothing to help LeCure while being rendered impotent by Cain. It was Cain's second complete game in three starts, and he's allowed one run over his last 34 innings.

The Reds only reached third base once all night as they were beaten by a complete game for the first time this season. But with one out, Rolen was running on contact when Nix grounded to second base. The throw went to the plate and Rolen was easily thrown out in the fielder's-choice play. Of the Reds' seven hits, Phillips had three of them.

"When he's on, he's as tough as it gets," Baker said of Cain. "We centered some balls, especially [Orlando] Cabrera. He hit him hard all night. We just didn't find the holes tonight, especially when we needed it with runners in scoring position."

After Arthur Rhodes finished the seventh and started the eighth for another two-thirds of an inning of scoreless work, the Giants padded their lead against Reds reliever Nick Masset in another rough night for the non-Rhodes portion of the Reds bullpen.

With two outs in the eighth, Pat Burrell hit a double and Buster Posey was walked on four pitches. It led to RBI singles by Bengie Molina and Cain. In 31 games, Masset has a 7.20 ERA and has given up 20 earned runs in 25 innings. It equaled his earned runs allowed from all of last season when he pitched 76 innings over 54 games.

"We just have to figure out which guys, other than Arthur, can do what they're supposed to do," Baker said. "If not, we're going to kill Arthur."

The solution to that conundrum could come out of the one over who gets to start Sunday. Perhaps either LeCure or Bailey?

"If they ask me to possibly take on another role up here, then obviously I'm more than willing to do that," LeCure said. "If they want me to go down there and continue to work on things in the Minor Leagues, that's up to them. I understand that's the reality of it."