Orioles 4, Blue Jays 1 (Game 1): Adam Jones hit a two-run homer and Steve Johnson turned in five strong innings in a rare start as host Baltimore took the opener of a doubleheader against Toronto.

Jones went 4-for-4 with two runs scored and a stolen base and Ryan Flaherty added a solo blast for the Orioles, who lost the nightcap 9-5 to fall 1 1/2 games behind the New York Yankees in the American League East.

Henderson Alvarez (9-14) started for the Blue Jays and was strong through three innings before running into trouble in the fourth. Chris Davis drew a leadoff walk and Alvarez left a 1-1 fastball belt high to Jones, who blasted it halfway up the first level in left field for his 32nd homer and a 2-0 lead.

Johnson (4-0) was summoned out of the bullpen for the spot start and scattered three hits while walking three and striking out six in five innings. Three relievers bridged the gap to Jim Johnson, who worked a scoreless ninth for his major league-leading 48th save.

Flaherty’s fifth homer made it a 3-0 gap in the fifth inning and Jones scored on a double-play grounder in the sixth to provide more insurance.

GAME NOTEBOOK: Toronto will send Ricky Romero to the mound in the nightcap. … Davis started in right field and made a diving catch to his right to rob Adeiny Hechavarria of a hit in the seventh. … Orioles pitcher Randy Wolf will undergo an MRI exam on his left elbow on Tuesday. He has been bothered since his start Saturday against the Red Sox.