BOSTON -- Rick Porcello is already paid like an ace. Lately, he's been pitching like one too.

Porcello signed a four-year, $82.5 million extension last April before even throwing a single pitch as a member of the Boston Red Sox, but struggled to the tune of a 9-15 season and tied career lows with a 4.92 ERA and 103 runs allowed.

This year, Porcello looks like a new man -- one who is worthy of his hefty price tag.

"Winning games," Porcello said of his motivation after tossing seven scoreless innings and striking out six in an 8-0 rout of the New York Yankees on Saturday night at Fenway Park. "That's why we're here. Go out there and win, so that's enough motivation for me."

Porcello (5-0) allowed five hits and a walk en route to his fifth straight win to open the season. He becomes the second Red Sox pitcher to win his first five outings since Josh Beckett won seven straight to begin the 2007 season. Clay Buchholz also won his first six in 2013.

"It was a lot of fun playing behind him (tonight)," Red Sox center fielder Jackie Bradley Jr. said. "He was definitely able to give us a chance to win, and we're very luck that we had him on our side tonight."

Bradley Jr. and Mookie Betts sparked the Red Sox offense, driving in three runs a piece, while David Ortiz hit his second home run in as many nights and Brock Holt added an RBI.

Boston (14-10) has a chance to sweep a three-game series with New York (8-14) in Sunday night's nationally-televised finale.

The Yankees have scored three runs or fewer in 17 of their 22 games.

"It's frustrating for all of us, what we're going through," said Yankees manager Joe Girardi, whose team is off to its worst start since opening 8-17 in 1984.

On the bright side, the '84 Yankees did go on to win 87 games.

"Track record tells you it's going to turn around," Girardi said. "I'm not going to lose faith in them. I'm not in the business of losing faith."

Bradley socked three hits and a pair of run-scoring triples, his team-leading third and fourth of the season, to give him nine RBIs in his last seven games.

"I'm comfortable," said Bradley, who is 8-for-16 with runners in scoring position this season. "I'm in a good place, mentally (and) physically. I've worked really hard to get where I am now, and I'm going to continue to work."

Michael Pineda (1-3) lasted just five innings, giving up two runs on five hits and three walks while striking out three for New York (8-14).

Pineda has coughed up 11 runs on 22 hits over his last three starts.

"It's tough because you believe (in) your team," Pineda said. "Everything's going to be better. We'll be OK. You continue grinding and fighting every day and everything can be better."

Brian McCann had two of his team's five hits as the Yankees lost their fourth in a row.

Bradley's first triple rolled to the center field triangle and Betts' infield single the next at-bat brought him in as the Red Sox doubled their lead to 4-0 in the sixth.

An inning later, Ortiz cleared the bullpens in right field with his blast and Holt reached on an error to score another run before Bradley Jr. laced a two-run triple down the line in right.

Betts' two-out bloop double in the second inning plated two to give Boston an early lead.

Porcello kept the Yankees bats silent early on and flashed his glove in the fifth, diving behind the bag at third to stop an errant throw from Red Sox left fielder Brock Holt.

Didi Gregorious took advantage of the shift on Chase Headley's single that deflected off Boston third baseman Travis Shaw's glove and rolled into left field, advancing to third after a foot race to the unattended base with Shaw, who was stationed at shortstop.

Holt's throw sailed past Shaw, but Porcello's potentially run-saving dive kept it in play.

Porcello got Jacoby Ellsbury to ground out in the next at-bat to squash the threat.

"I don't know if I had to dive," Porcello joked. "I played it out a little bit too much."

NOTES: New York's .236 team batting average ranked 23rd, and its 74 runs scored were the second-fewest in the majors entering Saturday. Boston's .277 average ranked second, and its 118 runs were tied for sixth. ... Yankees 3B Chase Headley, hitting .140 (8-for-57) coming in, was dropped to the bottom of the batting order. He went 1-for-3 on Saturday. ... New York's starting outfield of LF Brett Gardner, CF Jacoby Ellsbury, and RF Carlos Beltran have committed just one error on 92 chances over 478 combined innings in 21 games. ... Boston recalled INF Marco Hernandez from Triple-A Pawtucket and optioned RHP Pat Light to Pawtucket before Saturday's game. ... Red Sox RHP Carson Smith (right elbow strain) made his second rehab appearance for Double-A Portland against Reading on Saturday. Smith struck out one in an inning to earn a hold and is expected to be available early next week. ... Yankees RHP Nathan Eovaldi (1-2, 4.38 ERA) opposes Red Sox LHP David Price (3-0, 5.76) in Sunday's series finale.