Jose Altuve hit his first grand slam after Boston shortstop Xander Bogaerts made a mental gaffe on a play that would have ended an inning Sunday, carrying the Houston Astros to an 8-1 victory over the Red Sox.
Altuve, who leads the majors in hits, went 4 for 5, raising his hit total to 173 and majors' best average to .339 as the Astros completed a split of the four-game series.
Dexter Fowler and Jon Singleton added solo homers for Houston, which earned its 52nd win to surpass last year's total.
Daniel Nava had an RBI double for Boston.
Collin McHugh (6-9) gave up one run on seven hits in six innings for Houston.
Joe Kelly (0-1) was tagged for seven runs on seven hits, walking six over four innings in his Fenway Park debut with the Red Sox. He was acquired at the non-waiver trade deadline along with first baseman/outfielder Allen Craig for right-hander John Lackey.
Red Sox manager John Farrell was ejected by first-base umpire Doug Eddings after Altuve's slam.
Leading 2-0, the Astros got a break when manager Bo Porter won a challenge and they scored four runs after Bogaerts' mistake. The shortstop picked up Marwin Gonzalez's grounder, ran to second for what looked like a force and fired to first. The problem was he threw the ball about a step before he tagged the bag. After Kelly walked the bases full, Altuve homered into the Green Monster seats.
Farrell came out after the homer and was tossed.
Fowler's homer in the third made it 7-0.
Astros 1B Jesus Guzman, on the DL since August 2 with back spasms and on a rehab assignment with Triple-A Oklahoma City, is eligible to come off.
Red Sox 2B Dustin Pedroia was out sick and it was his 31st birthday. He had three homers in seven previous games on his birthday.
The Astros are off Monday before opening a three-game series at Yankee Stadium Tuesday when LHP Brett Oberholtzer (4-8, 3.87 ERA) is scheduled to face New York's lefty Chris Capuano (1-3, 4.13).
RHP Brandon Workman (1-6, 4.45 ERA) is slated to go for Boston Monday, facing C. J. Wilson (9-8, 4.71 ERA) when the Red Sox open a three-game series against the Los Angeles Angels.
Actor Matthew McConaughey watched the game from the second row down the left-field line just past the Astros' dugout. He appeared to go fairly unnoticed until he left in the top of the ninth and many fans took pictures and shook hands as he was walking out.