The win increases Boston's lead in the American League East to a season-high four games over the Orioles, who are tied with the Blue Jays for the two AL Wild Cards. The magic number for the 86-64 Red Sox to clinch the division is now in single digits at nine, with 12 games left.
"It's huge," said Betts. "Anytime you can come into somebody else's place and win, that's huge, but obviously, we have three more left and they're a really good ballclub. We're pretty good too, so it's going to be a good series."
David Ortiz also belted his 35th homer for the Red Sox as part of a three-run fifth inning while Rick Porcello (21-4, 3.08 ERA) held an impressive Baltimore lineup to two runs while pitching his third complete game of the season.
"He had great command. You see on the board the number of strikes," Orioles manager Buck Showalter said of Porcello. "It wasn't like we were swinging at a lot of pitches outside the zone either. That's why he won 21 games. It's not always the guy who throws the hardest, even though he's got plenty of that. A lot of different pitches and command of them."
Mark Trumbo doubled in the Orioles' first run in the fourth inning, with Adam Jones hitting a solo homer off Porcello in the eighth. Baltimore rookie starter Dylan Bundy was charged with five runs over five innings in the loss.
"Up to this point right now, this is the biggest series of the year for us," said Porcello. "So you know we've got to beat these guys up front and we have three more games left. It's a good way to start it."
The 35 homers by Ortiz are the most by a player age 40 or older, surpassing the previous record by Darrell Evans in 1987. If Ortiz goes deep just once more before the end of the regular season, he will break Dave Kingman's record in 1986 for most in a final season.
MOMENTS THAT MATTERED Porcello's precision: The most impressive thing about Porcello's latest strong performance was his efficiency. The sinkerballer threw 10 pitches or fewer in six of his nine innings and didn't throw more than 14 pitches in any inning. It was the 11th consecutive start Porcello has gone seven innings or more while allowing three earned runs or fewer.
"Rick Porcello was outstanding," said Red Sox manager John Farrell. "He threw a high number of first-pitch strikes. He was able to induce ground balls. He elevated at appropriate times. He had four pitches working for strikes tonight. He was in complete command for this one." More >
Bundy falters: The O's righty labored early and has a 6.62 ERA over his past seven starts. Bundy, who hasn't recorded a quality start since Aug. 22, allowed a pair of homers and is pitching in uncharted territory this late in the season.
"You can say [I had rough innings early all] that all you want, but I wasn't making quality pitches and they were putting quality barrel on it," said Bundy, who said his arm feels great. "That's all there was to it." More >
Mookie's second home: The eight homers by Betts in Baltimore are the most by a Red Sox player in a visiting park since Jimmie Foxx hit that many in 1939 in St. Louis against the Browns. Betts has six homers in the 65 road games he's played everywhere else this season. Betts had been struggling of late, and the home run was his first in September. Nine of the 31 homers Betts has hit this season have been against Baltimore.
"I have no idea. I try to do it everywhere, but it seems like it only works here," said Betts of his success in Baltimore. More >
Machado takes exception to HBP:Manny Machado was hit by Porcello's pitch in the fourth inning -- with Porcello working on a then-perfect game -- and he was not happy about it. Machado glared at Porcello before taking his base, with the Red Sox starter jawing back about the unintentional nature of the pitch. Machado went on to score on Trumbo's double.
"We were just walking to first base, just talking. Talking like human beings. Nothing much was said," Machado said. "We all know he doesn't want to hit me there in that situation. I know who we've got behind me. I'm not dumb. We've got Trumbo, [Chris] Davis, guys who with one swing of the bat can drive in a couple runs. There's nothing much to it honestly."
"It's September baseball," said Porcello. "Obviously emotions are running high. Nobody wants to get hit by a pitch, that's why I completely understand. I wouldn't like it if I was up there and I got hit.
"At the same time, there's absolutely no reason why I would hit him right there, especially with Mark Trumbo standing on deck. I mean, he's hitting missiles all over the ballpark off me. So I don't want to face him in a 2-0 game, especially when I got a perfect game going."
"It hurts. … There's an initial reaction. Manny understands. It's not que sera sera, you're happy about everything. … I can understand Manny's reaction." -- Showalter, on Machado's hit-by-pitch
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Porcello's 89-pitch complete game is the most efficient in the Majors this season, and shortest by number of pitches since Jeff Samardzija threw 88 for the White Sox on Sept. 21, 2015.
WHAT'S NEXT Red Sox:Eduardo Rodriguez was en route to a masterpiece last time he pitched at Camden Yards, but he had to leave after four no-hit innings on Aug. 16 due to a left hamstring injury. Rodriguez takes the ball in Game 2 of this four-game set on Tuesday night, with the first pitch set for 7:05 p.m. ET. The lefty is looking for his first win since July 16.
Orioles:Kevin Gausman will look to stifle the Red Sox's offense for the second time in six days. He held Boston scoreless over eight innings in his last start. The 25-year-old has been terrific lately, posting a 2.06 ERA since Aug. 3.