Lynn was not as aggressive as he would have liked to be in his last start, in which he got knocked around for five runs on nine hits against the Tigers.
"The outings that I've had where I've been less successful, I've been behind in counts," Lynn said. "That's usually going to hurt you, no matter who you are."
Lynn (10-3, 2.80 ERA) can continue his strong case for his first All-Star Game appearance this season. The 25-year-old right-hander is tied for second in the National League in wins and his 90 strikeouts are top-10 in the league.
Sanchez was saddled with the loss while giving up four runs -- three of them earned -- over six innings in Houston on Monday. He struggled with his control in his longest outing of the season, walking four -- including one with the bases loaded -- and hitting two batters.
Sanchez hasn't won a game since his first appearance of the season on April 8 -- although he's allowed two earned runs or fewer in four of his eight starts this season.
Sanchez will have his hands full against a St. Louis lineup that scored a combined 19 runs in the first two games of the series. With Jon Jay and Matt Carpenter both healthy, the Cards are feeling more confident in their offensive abilities.
"When we put this club together, we thought we had the right talent to win," Cards general manager John Mozeliak said. "Now that we're getting healthy, we feel better about that for sure."
Cardinals: C. Carpenter making strides
Ace Chris Carpenter threw live batting practice on Friday afternoon at Kauffman Stadium before watching his team beat the Royals, 11-4.
Carpenter threw 32 pitches to five different hitters in his first time facing batters since March 18. The right-hander is on the 60-day disabled list while recovering from a shoulder injury.
"I was happy with it," Carpenter said. "I was excited about being out there."
Carpenter will repeat the workout on Monday, and will be cleared to begin a Minor League rehab assignment if all goes well. The minimum number of appearances Carpenter could make at the Minor League level has yet to be determined.
Mozeliak said the timetable for Carpenter's recovery will be key as the club gets closer to the Trade Deadline.
Cardinals designated hitters entered Saturday as the all-time leaders among National League teams in batting (.314; 140-for-446), on-base percentage (.390) and slugging (.527). Matt Holliday, Carlos Beltran and Allen Craig have gone a combined 7-for-17 with three walks as DHs this season.
Royals: Bueno promoted, Colon designated
Francisley Bueno was promoted from Triple-A Omaha on Saturday and right-hander Roman Colon was designated for assignment.
Bueno made his Major League debut four years ago, and hadn't pitched in the big leagues since before tossing one inning of relief in Saturday's 8-2 loss.
Catcher Salvador Perez was given the day off on Saturday after playing in his first game following a four-month stint on the disabled list on Friday. Perez went 2-for-4 with a two-run homer in his return. The Royals are now carrying three catchers with Humberto Quintero and Brayan Pena still on board.
In six appearances against St. Louis -- five of them starts -- Sanchez is 3-0 with a 2.78 ERA. Current Cardinals hitters are batting .188 off Sanchez. Rafael Furcal and Matt Holliday have the most experience against the lefty. Furcal is 5-for-26 with two homers, while Holliday is 4-for-24.
Thirteen of the Royals last 16 games have been decided by two runs or fewer, seven of which were one-run games. Kansas City is 11-9 this season in one-run decisions and 8-10 in two-run games.
The Cardinals are 7-7 in Interleague Play entering Sunday's series finale.