Detroit closed the gap on American League Central leader Kansas City to just one game by beating the Royals 9-5 , with Torii Hunter having two hits in a six-run third innings which effectively decided the contest.
The tight fight for the Central was in marked contrast to the other two AL divisions, where Baltimore and the Los Angeles Angels both won to stretch the leads in the East and West respectively to ten and eight games.
In the National League, Washington's lead in the East reached equally prodigious proportions by beating nearest rival Atlanta and the Los Angeles Dodgers defeated San Diego to move 3-1/2 games clear in the West.
Angels' starter Jered Weaver became the first 16-game winner in the AL this season, steering his team to a 12-3 win over Cleveland.
Washington's Doug Fister pitched seven scoreless innings to steer the Nationals to a 2-1 win over Atlanta in the opening game of a three-game series between the top two NL East teams.
The Los Angeles Dodgers won 9-4 at home against San Diego, with Clayton Kershaw becoming the major leagues' first 18-game winner.
St. Louis' Matt Carpenter broke a scoreless tie with a two-run single in the seventh inning and Matt Adams added a three-run homer to give the Cardinals a 5-0 win over Cincinnati.
Baltimore's Nelson Cruz had a pair of hits to help the Orioles beat Boston 4-0.
Oakland's fading AL West hopes took another hit with a 5-4 loss over 12 innings at the Chicago White Sox, with Tyler Flowers hitting a tying solo homer in the ninth and then another drive in the 12th.
Miami's Giancarlo Stanton hit his 37th homer of the season, tying the Marlins' record for career homers at 154, as the hosts beat Milwaukee 6-4.
Seattle's Brad Miller had a tiebreaking two-run triple in the eighth inning and drove in three runs, helping the Mariners beat Houston 4-1 and close within a game of Oakland for the top AL wild-card spot.
Pittsburgh's Starling Marte hit a two-run homer to lead the Pirates to a 6-4 win at Philadelphia; their fourth consecutive victory.
Toronto's Marcus Stroman pitched a shutout in his first complete game, guiding the Blue Jays to an 8-0 win over the Chicago Cubs.
New York's Curtis Granderson hit a tying triple in the ninth and scored two pitches later on Wilmer Flores' sacrifice fly, sending the Mets to a 3-2 win over Colorado.