Pittsburgh @ Houston preview

Last Meeting ( Aug 30, 2011 ) Pittsburgh 2, Houston 8

THE STORY: Houston tries for a fourth straight victory and a three-game series sweep Wednesday night when it hosts National League Central rival Pittsburgh. The Astros followed Monday's 7-4 comeback win with an 8-2 rout on Tuesday behind three RBIs from J.D. Martinez. Houston broke the game open with six runs in the sixth inning.

TV: 8:05 p.m. ET, ROOT Sports (Pittsburgh); Fox Sports, Dish 447/9517 & DirecTV 678 (Houston)

PITCHING MATCHUP: Pirates RH James McDonald (8-6, 4.22 ERA) vs. Astros LH J.A. Happ (4-15, 6.03 ERA)

McDonald has steadied himself somewhat after being spotty all season, allowing three runs or fewer in each of his last four starts. Pittsburgh dropped both of his last two outings after his departure, with McDonald twice yielding three runs in six innings. In two starts against the Astros this season, McDonald earned a road win June 16 (5 2/3 IP, 7 H, 3 ER) and was robbed of another May 8 after allowing just three hits over six shutout innings. Houston hitters are 10-for-47 (.213) against McDonald.

The Astros have won just one of Happ's last 15 starts, and a great deal of that can be attributed to his performance — the lefthander has a 7.44 ERA since the end of May with a strikeout-to-walk ratio of 50:46. Happ has pitched his best this year against the Pirates, posting a respectable 3.27 ERA (4 runs, 11 innings) in two no-decisions. Pittsburgh CF Andrew McCutchen is 6-for-16 (.375) with a home run against Happ, and reserve OF Matt Diaz (8-for-15, HR) will likely find his way into the lineup as well.

ABOUT THE PIRATES (62-73): Offense has been a weak spot all season for Pittsburgh, which has been mired in a 9-26 funk since it was tied for first in the National League Central on the morning of July 25. The Pirates are 25th in the major leagues with 519 runs scored and have hit just 90 home runs, with 20 of those coming off the bat of CF Andrew McCutchen. Both McCutchen (81 RBIs) and 2B Neil Walker are hitting .274 to lead all Pittsburgh regulars.

ABOUT THE ASTROS (46-90): Houston created several holes in its lineup with salary-dumping deals last month, but it has been able to make up for it with solid contributions from some new faces. 2B Jose Altuve, who homered and drove in a pair of runs Tuesday, is batting .313 in his 38 major league games, while Martinez is hitting .295 with five homers and 29 RBIs since making his debut on July 30. The Astros have scored 19 runs during their current three-game win streak.

FINAL PITCH: When losing the first two games of a series, Pittsburgh has won the third game just 10 times in its last 52 tries.