Travis Hafner hit his 10th career grand slam — first since May 7, 2007 — in an eight-run eighth inning against Boston's bullpen. Boof Bonser and Joe Nelson combined to throw 60 pitches to 14 batters, walking five and allowing seven hits.
Masterson (2-5) faced the Red Sox for the first time and earned his second straight win after a long losing streak. The right-hander struck out six, walked two and allowed a pair of harmless one-out singles — to Victor Martinez in the third inning and J.D. Drew in the fifth.
The complete-game shutout was the first by an Indians pitcher against Boston since Jack McDowell on April 15, 1996.
Clay Buchholz (8-4) had a six-start winning streak snapped as Boston lost for the second time in its last 11 road games. The right-hander allowed only three hits over seven innings and trailed 3-0 when Bonser took over.
Masterson was 0-11 over 17 starts from Aug. 25 until beating the Chicago White Sox on June 4. In that win, he walked a season-high six over 5 2/3 innings in a 10-1 victory.
Masterson was sent from Boston to Cleveland with two minor league pitchers for Martinez, an All-Star catcher, just before last year's trade deadline.
Buchholz, the subject of trade rumors then, already has set a career high in wins this season. He was 5-0 with a 0.99 ERA in his previous five starts.
Trevor Crowe scored three times for Cleveland, which improved to 4-13 in its last 17 home games.
Crowe singled and tripled his first two times up. He scored in the first inning on a sacrifice fly by Jhonny Peralta, ending Buchholz's scoreless streak at 18 innings.
Crowe scored in the third as Austin Kearns grounded into a double play.
Peralta singled to start the fourth, took second on a wild pitch, third on a groundout and scored on another wild pitch.
Crowe walked and eventually scored on a broken-bat single by Russell Branyan off Bonser in the eighth. Peralta followed with another broken-bat RBI single off Nelson before Hafner delivered.
Hafner's six grand slams in 2006 tied a major league record. … Boston RHP Daisuke Matsuzaka, who won the series opener Monday, was sent back to the team's hotel because of the stomach flu. … Red Sox 2B Dustin Pedroia is 0-for-11 in the first three games of the series and has hit only .168 (17-for-101) in his last 25 games. … Boston is 17-4 against Cleveland since trailing the Indians 3-1 in the 2007 AL championship series. … Indians manager Manny Acta met Cleveland's No. 8 draft choice, high school catcher Alex Lavisky, and gave him a gentle but positive sales pitch: "I can't talk to you about money, whether to go to college or any of that, but I can tell you the people here in this organization are great baseball people." Lavisky, from suburban Lakewood, was thrilled to meet Cleveland first-base coach and former catcher Sandy Alomar Jr.