St. Louis Cardinals starting pitcher Mitchell Boggs delivers during the first inning of the Cardinals' 5-1 victory. St. Louis snapped the Royals' six-game winning streak Saturday in Kansas City, Mo.

Kansas City, Mo. ? The deeper he gets into his first big-league season, the better Mitchell Boggs seems to pitch.

Working his way out of some tough spots early, the rookie right-hander went six innings Saturday night, allowing four hits and one run and leading the St. Louis Cardinals to a 5-1 victory over a Kansas City team that had won 11 of 12.

Boggs (3-0) said his breaking pitch was actually better than in his first four starts.

“Absolutely,” said Boggs, who walked four and struck out six. “It’s been a little bit erratic my first couple of starts, not as consistent. Tonight it was better. It’s something I’ll continue to work on and build on.”

Rick Ankiel hit a two-run home run for a 4-0 lead over Kyle Davies in the sixth as the Cardinals beat the Royals for the first time in five games and halted K.C.’s six-game winning streak.

The Cardinals are 4-0 in the four starts the 24-year-old Boggs has made since being called up on June 6 from Triple-A Memphis.

“They’re 4-0 when I start because they’re killing the ball when I pitch,” he said.

A sellout crowd of 37,537, the biggest of the year in Kansas City, kept the stadium rocking.