PHILADELPHIA -- Clay Buchholz combined with two relievers on a three-hit shutout and the Boston Red Sox hit five home runs to batter the Philadelphia Phillies 8-0 in a season opener Monday afternoon.

Second baseman Dustin Pedroia and left fielder Hanley Ramirez each hit two homers for Boston, with the second by Ramirez a ninth-inning grand slam off reliever Jake Diekman.

Buchholz, making his first Opening Day start after going 8-11 with a 5.34 ERA in 2014, did not allow a hit until first baseman Ryan Howard doubled on an 0-2 pitch with two outs in the fourth. Phillies catcher Carlos Ruiz and right fielder Grady Sizemore also lashed back-to-back singles in the seventh, though Buchholz escaped the inning unscathed.

The Phillies managed just two other runners against Buchholz -- second baseman Chase Utley, who reached on the pitcher's two-out error in the first, and Ruiz, who walked in the fourth. It was the only walk issued by Buchholz, who struck out nine.

Red Sox relievers Junichi Tazawa and Tommy Lane each worked a scoreless inning in relief.

Philadelphia starter Cole Hamels, the subject of offseason trade speculation to Boston, lasted just five innings to take the loss. He allowed five hits, four of them homers, while striking out six and walking three.

Pedroia, who went 3-for-5, homered off the Philadelphia starter in the first and fifth.

Centerfielder Mookie Betts and Ramirez hit solo shots off Hamels in the third and fifth, respectively, with Ramirez's homer coming two batters after the one by Pedroia.

Hamels was making his second Opening Day start. He was beaten in his previous one, at Atlanta in 2013, and has lost his season debut each of the last five years. He is 1-6 over nine such starts in his career, and the Phils are 2-7 in those games.

Pedroia, who hit just seven homers in 135 games in 2014 and nine in 160 games the season before, launched Hamels' fifth pitch of the game, a 1-1 fastball, into the seats in left field. He also homered on a 1-1 fastball with one out in the fifth.

It was the fourth multihomer game of Pedroia's career, and his first since Sept. 13, 2011, against Toronto.

Ramirez, signed as a free agent in November after three years with the Dodgers, lined Hamels' change-up into the left-field seats for his first homer, with two outs in the fifth. In the ninth he hit an 0-2 slider from Diekman out. It was his sixth career grand slam, and his first since July 2, 2011, when he hit one against Texas while with the Florida Marlins.

Betts' homer led off the third with his homer, on a first-pitch fastball from Hamels. The 22-year-old Betts became the third-youngest Boston player to hit an Opening Day homer. Tony Conigliaro did it at age 20 in 1965, as did 21-year-old Tom Winsett in 1931.

NOTES: Boston RF Shane Victorino, who played his seven seasons in Philadelphia, was accorded warm ovations during pregame introductions and before his first at-bat, in the second inning. Victorino went 0-for-2 with two walks. He also stole a base. ... The Phillies opened their season at home for the first time since 2011. ... The two teams met 100 years ago, in the 1915 World Series, with the Red Sox winning in five games. ... It was the first time the Red Sox began their season against the Phillies, and the first time they opened against an NL team. Boston has, however, opened in Philadelphia on 10 previous occasions, all against the old Athletics. ... The Red Sox had two players in their starting lineup younger than 23, CF Mookie Betts and SS Xander Bogaerts, the first time Boston had two players that young in their Opening Day lineup since RF Tony Conigliaro and 2B Reggie Smith opened the 1967 season. ... Phillies CF Odubel Herrera is just the second rookie to make Philadelphia’s Opening Day roster since 1970. The other was INF Freddy Galvis in 2012.