CINCINNATI -- When Bronson Arroyo showed up the first time with his long, skinny sideburns and long, highlighted hair, no one was quite sure what to make of him.
A month later, the Cincinnati Reds love everything about him.
Arroyo stayed unbeaten in Cincinnati by pitching a four-hitter for the second complete game of his career, and the Reds beat the St. Louis Cardinals 6-1 Monday night in a matchup of the NL's top two teams.
"They're the No. 1 team in the division," said Arroyo, who threw only 109 pitches. "It was nice to shut them down. Any time you go up against those guys, you want to show that you can play with them."
Cincinnati set a club record with 17 victories in April, and started a new month with the same winning formula -- a lot of offense, a little dazzling pitching.
Rich Aurilia hit a solo homer, and Felipe Lopez broke an 0-for-17 slump with a run-scoring single and a bases-loaded single, driving in three runs all together. Every Reds starter except Arroyo had a hit off left-hander Mark Mulder (2-1), who was denied his 100th career win.
"I just left a lot of pitches up as the day went along," Mulder said. "Just one of them days."
The biggest change in the Reds is the addition of Arroyo (5-0), who has dramatically improved a rotation that was the NL's worst last season. The right-hander is the first Reds starter to win his first five decisions since Paul Wilson went 7-0 in 2004.
"He's been outstanding," Lopez said. "You can't say enough about what he's done. He's helped a lot.
"He brings the personality of being on a winning team. He has a lot of experience in the postseason, and we're feeding off that."
Arroyo extended the best start of his career by limiting the Cardinals to Juan Encarnacion's solo homer, three other harmless hits and three walks. His only other complete game was for Pittsburgh on Oct. 2, 2001, against the Mets.
Arroyo made 29 forgettable starts for Pittsburgh from 2000-02, before the Red Sox claimed him off waivers. In his return to the NL, he has grabbed everyone's attention.
"We didn't see him," Cardinals manager Tony La Russa said of Arroyo's first time through the NL. "He was in Pittsburgh and then went off to the other league. I just know he's doing a lot of things well now."
Arroyo became the first Reds pitcher to go eight innings in three consecutive starts since Jose Rijo in 1994.
The victory left Cincinnati (18-8) in sole possession of first place in the NL Central, a game ahead of the defending champion Cardinals.
Arroyo did his best work against Albert Pujols, who had his way with the Reds during a three-homer game on April 14 in St. Louis. Pujols leads the majors with 14 homers, a record for April.
"I tried to take him out of the equation," Arroyo said. "He helped me out with a couple of nice popups early."
Pujols flied out twice, popped out and walked, leaving it up to the rest of the Cardinals' lineup to prove itself. With their big hitter held in check, the Cardinals had no chance.
Arroyo has been the Reds' best starter by far, making new general manager Wayne Krivsky's first major move look good. Cincinnati acquired the right-hander from Boston for outfielder Wily Mo Pena on March 20.
Arroyo allowed only one hit in eight innings of a 5-0 victory in Washington on Wednesday. He extended his streak of scoreless innings to 16 before Encarnacion hit a solo homer into the upper deck in left field in the second inning, his second homer in two games.
Aurilia's fifth homer barely cleared the right-field wall in the first inning and started the Reds' offense rolling. Lopez's two-out, run-scoring single put the Reds up 2-1 in the fifth and snapped the shortstop's 0-for-17 slump. His bases-loaded single in the sixth off Josh Hancock completed a four-run rally that put the Reds in control.
- Cardinals 3B Scott Rolen stayed back in St. Louis to recover from a viral infection that has sidelined him for a week. The plan is for him to rejoin the club in Houston on Wednesday.
- C Yadier Molina went 0-for-3, extending his slump to 0-for-15.
- Reds CF Ken Griffey Jr. remains on the 15-day disabled list, recovering from an inflamed tendon behind his right knee. He was eligible to be activated on Friday, but the leg doesn't feel back to normal. "He ran a lot today and felt pretty good," manager Jerry Narron said. "He's just not 100 percent yet."
- Reds RHP Wilson will start for Triple-A Louisville on Tuesday, the second start on his rehabilitation stint. Wilson is recovering from shoulder surgery last June 17.