Boston made several outstanding defensive plays on hard-hit balls, but it was Castro's soft single over shortstop that finally fell. The right-hander retired Shane Victorino to end the eighth, and Daniel Bard worked a perfect ninth to finish the one-hitter.
Castro, filling in for injured shortstop Jimmy Rollins, looped a 3-1 pitch just out of Marco Scutaro's reach. The shortstop lunged with his glove and tumbled to the turf, but the ball dropped cleanly in short left field.
Matsuzaka (3-1) struck out five and walked four in his longest outing of the year. He was making his fifth start after beginning the season on the disabled list with a neck strain.
Matsuzaka has never pitched a shutout in the majors. His only complete game came on May 14, 2007, against Detroit, in his rookie season after coming over from Japan.
He got plenty of help from his defense in this one.
Chase Utley ripped a liner in the first inning, but was robbed of a hit on a leaping catch by Red Sox second baseman Dustin Pedroia. Utley also drove the ball to deep left-center in the fourth, but Jeremy Hermida made a running catch at the base of the wall in front of the 374-foot sign.
In the sixth, Scutaro ranged to his left and made a strong play to retire Placido Polanco and end the inning. And Matsuzaka also made a fine play by beating Victorino to first base by a step after taking the toss from David Ortiz on Victorino's grounder to first.
Matsuzaka ended the seventh by snaring Jayson Werth's line drive that appeared headed to center field for a hit. The pitcher paused for a second after making the excuse-me catch, appearing to look with surprise at his glove.
Boston continued its excellent defense in the eighth when third baseman Adrian Beltre dove to his left to rob Carlos Ruiz of a hit on a low line drive, then doubled off Raul Ibanez, who had walked, at first.
However, on the next batter, Scutaro came up inches short of making an over-the-shoulder grab on Castro's soft looper.
Boston chased Philadelphia starter Kyle Kendrick (2-2) in the fifth with four runs on five hits, including RBI doubles by Ortiz and Beltre. Kendrick went 4 2/3 innings and allowed five runs and eight hits.
Previously, Matsuzaka's longest outing this season was seven innings in a 6-1 win over Toronto on May 11. He allowed nine hits and seven earned runs in 4 2/3 innings in his last start, May 17 at Yankee Stadium, and had been tagged for 19 earned runs in his first four games this year.
Philadelphia played without Rollins, who was placed on the 15-day disabled list after re-injuring his right calf in Friday's 5-1 victory over Boston. Rollins had missed 29 games with a right calf strain before returning to the lineup Monday.
Notes
Matsuzaka singled in the second inning, marking his first career regular-season hit. He had been 0-for-8 with four strikeouts in the regular season. He did get a hit in the 2007 World Series. … Jacoby Ellsbury led off and played center field, marking his return to Boston's lineup after a 37-day stint on the DL with broken ribs. Ellsbury went 0-for-4 with a walk and a run scored. … Boston has had 18 no-hitters, the last by Jon Lester on May 19, 2008, in a 7-0 win over Kansas City. The last nine-inning no-hitter against the Philies was on April 16, 1978, when Bob Forsch did it in a 5-0 victory in St. Louis. Montreal's Pascual Perez pitched a five-inning no-hitter against Philadelphia on Sept. 24, 1988, in a 1-0 Expos win.