Pittsburgh @ Washington preview

Last Meeting ( May 25, 2014 ) Washington 5, Pittsburgh 2

After making themselves at home at Citi Field, the Washington Nationals return to the nation's capital to open a 10-game stretch with a three-game series versus the Pittsburgh Pirates on Friday. The Nationals completed a three-game sweep and recorded their franchise-best 11th consecutive victory at the New York Mets with a 4-1 triumph on Thursday. Adam LaRoche belted a two-run homer in that contest and has also gone deep to highlight a 3-for-5 career mark versus Friday starter Charlie Morton.

While Washington boosted its lead to six games over second-place Atlanta in the National League East, Pittsburgh has dropped four of six to fall 2 1/2 behind first-place Milwaukee in the NL Central and a half-game in back of St. Louis for the first wild card. To add injury to insult, infielder Jordy Mercer exited Thursday's 5-2 loss to Detroit with right forearm tightness. Manager Clint Hurdle refused to speculate on the severity of the injury or how long Mercer might be sidelined - "I'm not a doctor," he told reporters.

TV: 7:05 p.m. ET, ROOT (Pittsburgh), MASN (Washington)

PITCHING MATCHUP: Pirates RH Charlie Morton (5-11, 3.62 ERA) vs. Nationals RH Tanner Roark (11-7, 2.86)

Morton fell to 0-2 in his last seven outings after allowing five runs on as many hits in five innings of an 8-2 loss to San Diego on Sunday. The 30-year-old, who hasn't tasted victory since July 2, defeated Washington on May 23, permitting one run on five hits in 5 2/3 frames. Morton has struggled mightily on the road, posting a 2-7 mark with a 4.52 ERA.

Roark settled for a no-decision in his last outing on Saturday despite allowing one run on six hits in seven innings against Atlanta. The 27-year-old has been pretty consistent in that regard, yielding fewer than two runs 12 times in 23 starts. Roark, who has yet to face Pittsburgh in his brief career, has split 10 decisions at home this season despite a 2.40 ERA.

WALK-OFFS

1. Pittsburgh C Russell Martin is riding an 11-game hitting streak and is 3-for-5 with two runs scored against Washington this season.

2. Nationals RF Jayson Werth (shoulder) could come off the bench Friday and may even start Saturday's tilt, manager Matt Williams told MLB.com.

3. The Pirates claimed RHP John Axford off waivers from Cleveland and designated 1B Matt Hague for assignment.

PREDICTION: Nationals 5, Pirates 3