The Red Sox managed just four runners in the first six innings on two singles and two walks but none got past first base.
Nava walked with two outs in the second before Johnny Gomes popped out to second baseman Ryan Flaherty. Victorino started the fourth with a single but was caught stealing. Pedroia then walked before Napoli grounded into a double play.
Nava then singled with one out in the fifth, but Chen struck out Gomes and got David Ross to ground out to Flaherty.
NOTES: Boston RHP John Lackey is expected to miss his next start, scheduled for Friday, with inflammation in his right biceps. He walked off the mound with pain in his right arm in the fifth inning of Boston’s 5-0 loss at the Toronto Blue Jays, his first start after elbow surgery that sidelined him all last season. ... After an off day Tuesday, Jake Arrieta (0-0) pitches for the Orioles on Wednesday night against Ryan Dempster (0-1). ... Red Sox rookie LF Jackie Bradley Jr., got the day off after batting .143 in the first six games following an outstanding spring training that earned him a spot on the opening-day roster. ... The National Anthem was sung by the Jimmy Fund Chorus. This is the 60th year in which the Jimmy Fund, associated with the Dana-Farber Cancer Institute, has been the Red Sox official charity. ... Former astronaut Edwin “Buzz” Aldrin, the second person to walk on the moon, attended the game.