ST. LOUIS -- The #rallykitty phenomenon lived on Thursday night at Busch Stadium.

One night after Yadier Molina belted a grand slam on the first pitch after a kitten delayed the game by running on the field, pictures of cats hamming it up appeared on the scoreboard during late-game pitching changes.

Meanwhile, the St. Louis Cardinals' offense remained in heat, digging its suddenly sharp claws into the scratching post that was the Kansas City Royals' bullpen and unloading another slam to put their stamp on a sixth consecutive victory.

Dexter Fowler cracked a first-pitch slam in the bottom of the seventh to snap a tie and lift St. Louis to an 8-6 win, ensuring a four-game sweep of the I-70 interleague series and putting more pressure on the National League Central-leading Chicago Cubs.

Before his game-changing at-bat, Fowler and hitting coach John Mabry went back and forth on the proper approach to attacking reliever Neftali Feliz.

"We bounced some things off each other," Fowler said. "We had a healthy conversation. I'm not going to tell you who won."

Here's a hint: the Cardinals. Ambushing a 94 mph four-seam fastball, Fowler lofted it 404 feet into the bleachers behind St. Louis' bullpen in right-center for a 7-3 lead. It was his 15th homer of the year and his third career slam.

It marked the first time St. Louis (59-56) slugged slams in consecutive games since Aug. 31-Sept. 1, 2011. Pitcher Jake Westbrook and Molina did the honors then.

"We needed something to happen," Cardinals manager Mike Matheny said of Fowler's slam, "and that was something."

An inning earlier, St. Louis was struggling to crack the code on Royals starter Jason Hammel. Entering the sixth, Hammel had thrown 90 pitches, but he also had a two-hitter going and a 3-0 lead in his hip pocket.

Hammel hit Paul DeJong with a 1-2 pitch to start the sixth. Fowler worked a full count and lined a double off the wall in right-center, scoring DeJong. That was Hammel's final pitch.

Cue the Kansas City bullpen, and cue the Cardinals' offense. St. Louis pounced on five relievers as the tiny kitten pounced on the groundskeeper's arm Wednesday night as the animal was being carried off the field.

Reliever Peter Moylan took a potential double-play ball by Jose Martinez and tossed it into center field for a run, making it 3-2. Mike Minor came in and promptly ceded Kolten Wong's sacrifice fly to tie the game.

"Real nice job of staying the course," Matheny said. "We were having trouble generating much of anything early."

Minor (5-4) gave up a leadoff single to Matt Carpenter in the seventh. Feliz came in and coughed up a single to Tommy Pham, then walked DeJong to set the stage for Fowler.

The Royals (57-57), who lost for the sixth time in seven games, pulled within 7-6 in the eighth. Pinch hitter Brandon Moss lined a two-run double high off the right-center-field wall, and Whit Merrifield followed with a sacrifice fly.

However, Trevor Rosenthal, asked for a four-out save, stranded Moss at third by retiring Lorenzo Cain -- 4-for-4 before that at-bat -- on a fly ball to the warning track in right. Rosenthal then worked around Mike Moustakas' two-out single in the ninth for his 10th save in 12 chances.

Hammel gave up just three hits and two runs in five-plus innings, walking one and whiffing seven in a 103-pitch effort.

"Long at-bats, long innings," Hammel said. "The pitch count kind of got up there."

A Kansas City bullpen that has worked 20 1/3 innings starting with a Sunday doubleheader couldn't hold up. It was touched for six runs in three innings Thursday night, including an insurance tally in the eighth on DeJong's two-out double that scored Tommy Pham.

Lance Lynn got a no-decision for St. Louis, giving up six hits and three runs, two earned, over six innings. He tied a season high with five walks and fanned three. Lynn also survived a Cain liner off the right side of his head in the third.

Tyler Lyons (1-0) got the last two outs of the seventh to pick up the win. The result pushed the Cardinals within a game of the idle Cubs for first place.

NOTES: Kansas City placed RHP Trevor Cahill (right shoulder impingement) on the 10-day disabled list and recalled RHP Kevin McCarthy from Triple-A Omaha. McCarthy is 1-0 with a 2.14 ERA in 16 relief appearances with the Royals this year. ... St. Louis won Wednesday night despite allowing 15 hits, only the 14th time since 2000 the Cardinals were able to do that in a nine-inning game. ... Kansas City LF Alex Gordon was back in the lineup Thursday night, batting seventh after a two-game break from starting and going 1-for-3 to raise his average to .198.