Rapid reaction: Sox 7, Astros 3

BOSTON -- It took him five tries, but Ryan Dempster finally earned his first victory as a member of the Red Sox.

The veteran right-hander, who signed a two-year free-agent deal with Boston worth $26.5 million in the offseason, took advantage of the strikeout-prone Astros in claiming a 7-3 victory over Houston on Friday night at Fenway Park.

Dempster was amply backed by the Sox offense. Catcher David Ross led the way with a pair of solo homers and two singles in Boston’s season-high 17-hit attack.

Will Middlebrooks and red-hot David Ortiz also homered for the Sox, who banged out nine extra-base hits, including a pair of doubles by Dustin Pedroia (3-for-4).

Dempster whiffed 10, matching his season high, in a 104-pitch, four-hit, two-run, six-inning stint in improving to 1-2 for the season. Dempster now has fanned 43 in his five starts, totaling 30 innings this year. He is tops in strikeouts on the staff, which leads the majors in whiffs entering last night with 218.

He found a good match for his pinpoint fastball and tantalizing slider in the Astros. Houston entered the night leading the majors with 218 punchouts, comfortably ahead of both Boston and Cincinnati, which had 194 apiece.

Dempster fanned four in a row spanning the first and second innings. He struck out three batters in the fourth and had at least one whiff in each inning except the third. Dempster allowed single runs in the third and fifth innings, with third baseman Matt Dominguez, who had led off each inning with a double, scoring each time.

But the Sox had scored at least one run in each of the first five innings, so Dempster handed a 6-2 lead to Clayton Mortensen, who took over in the seventh. Mortensen, Junichi Tazawa, Koji Uehara and Alex Wilson finished up.

SETTING RECORDS: Mike Napoli’s RBI double in the third inning set a couple of Red Sox records for the month of April. It was his 17th extra-base hit and his 12th double. Jose Offerman had held the record with 16 extra-base hits in April 1999. Three other players had 11 doubles in the month. Napoli added an 18th extra-base hit, his 13th double, in the seventh.

Jacoby Ellsbury also set a record for April, swiping his 11th base, eclipsing the record of 10 he established in 2009. It was the 200th stolen base of his career, making him the third member of the Sox to reach that figure, joining Harry Hooper (300) and Tris Speaker (267).

ROCKY REHAB OUTING: Boston closer Joel Hanrahan, on the disabled list because of a hamstring issue, coughed up two runs on a double and a homer in his one inning for Pawtucket in Buffalo on Friday night. Eugenio Velez took him deep in the eighth inning, polishing off an 8-4 win for Buffalo. Hanrahan struck out one and did not walk a batter.

FEAST OR FAMINE: Will Middlebrooks, his latest skid reaching 2-for-16, fouled off a few pitches and then clubbed a 3-and-2 fastball for a long homer to left in the fourth inning. It was only Middlebrooks’ 15th hit of the year, but six have been homers. Middlebrooks, who entered the game batting a mere .169, leads the team in that category. He added an infield single in the eighth.

ROSS’ POWER SURGE: David Ross bashed solo homers off Erik Bedard in the second and fourth innings, accounting for the veteran catcher’s 11th career multiple-homer game. He last accomplished the feat exactly two years ago, while playing for Atlanta in San Diego. His second round-tripper was a back-to-back blast, following Middlebrooks’ long ball, the third time this year the Sox have hit consecutive homers.

GOMES GIVETH, TAKETH AWAY: Left fielder Jonny Gomes, not known for his defense, showed his unfamiliarity with the Green Monster in the fifth. He thought Matt Dominguez’ high fly would hit off the wall, so he peeled off, looking to field the carom. Unfortunately, the ball didn’t hit the wall. It landed on the warning track for a gift double. Dominguez eventually scored. But with two outs and a runner at first in the inning, Gomes raced to his right and made a diving, sliding catch of Jason Castro’s slicing liner in a highlight-reel play.

SEND HIM, SEND HIM!: As Pedro Ciriaco zipped past first base and then second base with Houston center fielder Robbie Grossman trying to track down his drive in the triangle, the anticipation in Fenway began to build. Would he be able to turn this into one of the game’s most exciting plays -- the inside-the-park home run?

Ciriaco steamed toward third base. But as he approached it, Red Sox third-base coach Brian Butterfield saw that the relay throw was heading toward shortstop Marwin Gonzalez, so he held up Ciriaco rather than take a two-out gamble. Unfortunately for Boston, Jacoby Ellsbury then grounded out to second, stranding Ciriaco.