Boston fell to their second-ever 0-3 start at Fenway Park and their first since 1948 as Trey Mancini and Austin Hays hit two-run doubles during a seven-run third inning that carried the Orioles to an 11-3 win Sunday.
Cedric Mullins went 5-for-5 with three doubles and a walk for the Orioles, collecting four hits in the first four innings. Maikel Franco added a first-inning, two-run double, helping Baltimore to its first three-game sweep at Fenway since Aug. 25-27, 2017.
"I think the synergy we have is really strong," Mullins said. "Guys have been playing with each other for a few years now."
In last year's pandemic-shortened season, the Orioles finished fourth in the American League East with a 25-35 record, coming off 108 losses in 2019 and a club-high 115 the previous year. This early sweep gives Baltimore its first one-game lead in the AL East since May 1, 2017.
Boston is coming off a 24-36 record last year, its worst winning percentage since 1965.
"We got beat in every aspect of the game," Boston manager Alex Cora said. "We're off to a rough start."
The Red Sox lost their first four home games in 1948, rebounded to tie Cleveland at 96-58 after the scheduled 154-game regular season and lost a tiebreaker playoff 8-3 at Fenway.
Making just his third major league appearance, Baltimore left-hander Bruce Zimmermann (1-0) gave up three runs and four hits in six innings with five strikeouts and one walk for his first MLB victory.
"It's a long season, but if anything, it gives a great confidence booster for this team," Zimmermann said. "I think we're going to surprise a lot of people this season."
The Orioles held the Red Sox to five total runs in the series.
"You've got to pitch in this league, and we pitched these three games," Orioles manager Brandon Hyde said. "We got really good starts from three guys, and our bullpen did a good job coming in and throwing strikes."
J.D. Martinez had a solo homer and an RBI double for the Red Sox.
Boston starter Garrett Richards (0-1) was chased with no outs after loading the bases in the third. He was charged with six runs and seven hits.
"It's three games into the season, kind of an early panic button," Richards said. "If we invested our entire take on three games, I don't think anybody would be able to predict a World Series winner. This is one series."
Taylor ultimately faced eight batters, getting two outs -- both strikeouts -- and giving up five hits and four runs.
Boston right-hander Garrett Whitlock came in for Taylor and pitched 3 1/3 scoreless innings in his major league debut, striking out five.
Cora said before the game that Mancini should be the Comeback Player of the Year.
"He should be the Comeback Player of the Year, regardless," Cora said. "He could hit .330 or .180, and he's the Comeback Player of the Year already. I know there are other guys coming back from injury, but to come back from that is amazing."
Mancini missed the 2020 season due to Stage 3 colon cancer, completed six months of chemotherapy and returned in spring training.
Orioles: Hays left the game after sliding into second base with right hamstring discomfort. ... Manager Brandon Hyde said right-hander Shawn Armstrong could be activated from the paternity list Monday. The pitcher's wife, Sarah, gave birth to a baby boy Wednesday.
Red Sox: Cora said before the game that "everything is trending that he'll be with us" about lefty starter Eduardo Rodríguez, who started the season on the injured list with left elbow inflammation. Rodríguez pitched a simulated game Friday at the club's new Triple-A facility in Worcester, Massachusetts.
Red Sox: RHP Nick Pivetta is slated to make his season debut against Tampa Bay on Monday at Fenway. Michael Wacha is set to make his first start with the Rays after signing a one-year, $3 million contract in December.
The Associated Press contributed to this report.