Jake Arrieta said he enjoyed running into some of his old Orioles teammates before Friday's game at Wrigley Field.
Then he had an even better time on the mound, shutting down Baltimore in his first start against his former club.
Arrieta held Baltimore to four hits in seven innings and Javier Baez homered again as the Chicago Cubs beat the Orioles 4-1.
"There was a little more to it, being your former team," Arrieta said. "You know after the first inning, it was just kind of business as usual."
The Orioles traded Arrieta to Chicago with reliever Pedro Strop in a multi-player deal during last season. He's turned into Chicago's ace this season.
"A really well-played game all the way around," Chicago manager Rick Renteria said. "The stage was actually set by Jake. Jake did a great job; a phenomenal seven innings of work."
Baez hit his sixth homer in his 18th game since getting called up from Triple-A, Luis Valbuena also homered, and Logan Watkins and Arismendy Alcantara each drove in runs with singles as the Cubs snapped AL East leading Baltimore's four-game winning streak.
Phillies 5, Cardinals 4: Ryan Howard drove in a pair of runs and Kyle Kendrick overcame a rocky first inning to lead the Phillies to a win in Philadelphia.
Ben Revere, who entered the day second in the NL in batting, went 3-for-4 to raise his average to .315. Chase Utley and Marlon Byrd also drove in runs for Philadelphia, which won its third in four games.
Matt Adams homered and Matt Holliday drove in two runs for the Cardinals, who lost for just the second time in nine games.
Kendrick (6-11) increased his first-inning ERA to 9.69 this season by allowing three early runs. He left after giving up four runs and eight hits in 6 1/3 innings.
Yankees 4, White Sox 3: Martin Prado hit an RBI single with two outs in the ninth inning, lifting the Yankees past the White Sox in New York.
Facing a full-count pitch from Daniel Webb (5-4) with the bases loaded, Prado lined a hit up the middle to complete the Yankees' comeback from three runs for their fourth win in 11 games.
Prado hit a two-run homer in the third, and Jacoby Ellsbury had an RBI double in the fifth off John Danks after Chicago's Jose Abreu connected for a three-run shot in the first against Shane Greene.
David Robertson (2-4) struck out two in a perfect ninth. Chicago (59-69) fell a season-high 10 games under .500.