Pujols, who attended Fort Osage High School just a few miles from Kauffman Stadium, leads the majors with 21 home runs and 53 RBI. Pujols hit the first pitch from Burgos over the center-field fence after David Eckstein walked and Scott Spiezio singled.
"He's amazing," Eckstein said. "He shows up every single day wanting to win bad. It just seems like when it is on him and to keep the momentum on our side, when we need a big hit he comes out and delivers."
Pujols, who hit a two-run homer on Friday in St. Louis' 9-6 victory, entered the series in an 0-for-12 skid. He has homered in back-to-back games seven times this season. He simplified his approach against Burgos.
"See the ball, hit it," Pujols said. "I was not trying to do too much. I got a pretty good pitch to hit and put my best swing the whole night. Our kid (Anthony Reyes) pitched an outstanding game and deserved to win. We got the win and that's the most important thing."
The Cardinals continued their dominance of their cross-state rivals, winning for the ninth time in the past 10 meetings. Kansas City has lost eight straight and dropped to 10-30, the worst record in franchise history after 40 games.
Reyes (1-0), just promoted from Triple-A Memphis and making his second major league start, held the Royals to four singles over 5 2/3 scoreless innings to earn the win. He walked one and struck out one.
"He moved the ball all over the zone and used four pitches," St. Louis manager Tony La Russa said. "He pitched to both sides of the plate and had command. He hit the catcher's glove most of the time. That was impressive."
But not impressive enough to keep him in the majors. It was only a spot start because of an injury to Sidney Ponson and La Russa said Reyes would be returning to the minors.
Reyes, a 24-year-old right-hander who was a 15th-round draft pick in 2003 out of Southern California, made his major league debut last Aug. 9 and beat Milwaukee.
"I try to take advantage of every opportunity that I get to pitch up here," Reyes said. "I come up the mind-set not to give them a reason to send me down. I had pretty much everything working. I was able to get ahead in the count."
Jason Isringhausen worked the ninth for his 14th save in 16 opportunities.
Denny Bautista (0-2), making his third start since coming off the disabled list with a strained pectoral muscle, gave up just one run and five hits in six innings. He struck out three, walked none and hit a batter, throwing 61 of his 100 pitches for strikes.
"That is a positive," Royals manager Buddy Bell said. "He was around the plate with most of his pitches."
The Royals scored two runs in the eighth to break a 13-inning scoreless drought. Andres Blanco led off the inning with a bunt single and stopped at second on Esteban German's pinch-hit single. Mark Grudzielanek singled off left-hander Randy Flores to score Blanco.
Reggie Sanders doubled to left to drive in German, but shortstop Eckstein threw out Grudzielanek, who ran past third-base coach Luis Silverio's stop sign, at the plate.
"By the time I saw it, I was already running," Grudzielanek said. "I probably would have broke a leg trying to stop. There was no way chance of stopping. I was trying to be aggressive and get some runs across."
Said Bell: "We made some mistakes. You can't make mistakes against this club and get away with it."
- Royals SS Angel Berroa, who has struck out 29 times while drawing only one walk and has eight extra-base hits in 143 at-bats, did not start for the first time this season. Blanco, who was called up Friday from Triple-A Omaha, started instead.
- Rolen was hit by pitches in back-to-back plate appearances. RHP Mike Wood hit Rolen in the ninth inning Friday, and Rolen was plunked leading off the second inning Saturday by Bautista.
- The Cardinals optioned RHP Brian Falkenborg to Memphis to make room for Reyes.
- The game was the Royals' second sellout of the season with a crowd of 40,516. Only the opening day attendance of 41,054 was larger.