James Shields pitched seven innings of two-hit baseball to guide the Kansas City Royals past the Detroit Tigers 3-0 in MLB.
In a clutch American League Central division clash, Shields struck out eight as he chalked up his 14th win of the season, which took the Royals one game clear of the Tigers.
Detroit's consolation, as it stands, is an AL wildcard spot.
Salvador Perez singled to score Josh Willingham at the top of the fourth, while later in the inning, Lorenzo Cain's hit got Eric Hosmer home to double Kansas City's lead.
Cain scored himself in the ninth inning, Alcides Escobar's sacrifice fly helping him home.
Tigers starter Rick Porcello's record this season slipped to 15-11, after pitching more than six innings for the concession of seven hits and two runs.
The Baltimore Orioles continued to canter towards the AL East title, a fourth straight win coming in the shape of a 10-6 result over the Boston Red Sox.
The loss for Boston mathematically ended their World Series defence.
The Toronto Blue Jays remain alive for a wildcard spot, an 11-1 win over the Chicago Cubs completing a series sweep and leaving them 3.5 games off a post-season place.
Joining the Tigers in the AL wildcard places are the Oakland Athletics, who were 2-1 losers to the Chicago White Sox.
The Seattle Mariners are half-a-game behind the Tigers in the wildcard race, after a 5-2 loss to the Houston Astros.
Also still in the hunt are the Cleveland Indians and New York Yankees, both 4.5 games behind.
The Yankees were 8-5 winners over the Tampa Bay Rays, while the Indians' clash with the Minnesota Twins was postponed due to rain - forcing the teams to play a double-header on Thursday.
National League Central leaders the St Louis Cardinals fell to back-to-back losses, going down 4-2 to the Cincinnati Reds to see their divisional lead cut to 3.5 games.
Looming large are the Pittsburgh Pirates - who occupy a wildcard spot - after a 6-3 victory over the Philadelphia Phillies.
NL West pace-setters the Los Angeles Dodgers were 4-0 victors over the San Diego Padres, to preserve their 2.5-game buffer on the San Francisco Giants.
The Giants - wildcard holders - also had a shutout win, silencing the Arizona Diamondbacks 5-0.
Leading the chasing pack for the NL wildcard places are the Atlanta Braves and Milwaukee Brewers, both 1.5 games back.
The Braves beat NL East rivals and runaway leaders the Washington Nationals 6-2, while the Brewers proved too good for the Miami Marlins 4-1.
The Colorado Rockies were eliminated from post-season contention on Wednesday, suffering a 2-0 loss to the New York Mets.