The Texas Rangers became the first team to 50 wins this season as Josh Hamilton's 25th homer helped them beat the Oakland Athletics 7-2.
Martin Perez got the win on his first big-league start, allowing two runs in 5 1/3 innings, backed by homers from Hamilton and Adrian Beltre.
Hamilton drove in four including his three-run shot, while Ian Kinsler knocked in a couple.
Anthony Rizzo's first home run with the Chicago Cubs proved to be the game-winning hit in a 3-2 victory over the Houston Astros.
Down 2-0 in the fifth, Starlin Castro drove in a run before Rizzo crushed a two-run shot which put the Cubs ahead for good.
Johan Santana hurled eight shutout frames to lead the New York Mets to a 5-0 win over the Los Angeles Dodgers.
Santana allowed three hits and two walks, striking out three, and got support from Ike Davis who hit a three-run homer in the sixth.
The New York Yankees got seven scoreless innings from Hiroki Kuroda in a 4-0 win over the Chicago White Sox.
Curtis Granderson hit his 23rd homer for the Yankees, Robinson Cano his 19th and Dewayne Wise also went yard.
Ryan Braun homered twice, taking his total for the season to a National League-leading 22, as the Milwaukee Brewers beat the Arizona Diamondbacks 10-2.
Mat Latos threw nine innings of one-run ball to give the Cincinnati Reds a 2-1 win over the San Francisco Giants.
Rick Porcello hurled seven scoreless frames to help the Detroit Tigers to a 6-2 win over the Tampa Bay Rays.
Stephen Strasburg could only manage three innings in heat of 106 Fahrenheit as the Washington Nationals slipped to a 7-5 defeat at the Atlanta Braves.
The Minnesota Twins took two wins from their double-header with the Kansas City Royals, winning the afternoon game 7-2 on the back of eight strong innings from Scott Diamond and doubling up with a 5-1 victory in the evening game.
Shin-Soo Choo had four hits including a home run as the Cleveland Indians claimed an 11-5 win over the Baltimore Orioles, who later announced they had traded for Jim Thome from the Philadelphia Phillies.
The Phillies lost 3-2 to the Miami Marlins.
Yasmani Grandal homered twice in his first Major League start to help the San Diego Padres beat the Colorado Rockies 8-4.
The Toronto Blue Jays beat the Los Angeles Angels 11-2, the Pittsburgh Pirates were 7-3 winners over the St Louis Cardinals and the Seattle Mariners edged the Boston Red Sox 3-2.