After the concern was alleviated earlier in the week, Strasburg seeks to end his five-start winless streak as Washington looks to avoid a third straight loss to the host Pittsburgh Pirates on Saturday.Since allowing three hits in seven innings of a 2-0 win over Miami on opening day April 1, Strasburg (1-4, 3.13 ERA) has gone winless with a 3.86 ERA while throwing at least 110 pitches four times.He walked four and gave up two runs in six innings of Washington's 3-2 loss to Atlanta on Monday, and manager Davey Johnson was concerned his ace was experiencing potentially serious arm trouble as he said Strasburg was shaking his arm between pitches more than normal.The right-hander, though, knew right away there weren't any major problems."I'm not missing my next start. I'll tell you that right now," Strasburg said after the game.General manager Mike Rizzo agreed."Stephen had some irritation on his forearm. He's healthy, happy and ready to pitch Saturday," Rizzo told the team's official website Tuesday. "He was seen by the team doctor here in the clubhouse and was given a clean bill of health."That's good news for the Nationals (15-15), as Strasburg has been dominant in his two career outings versus Pittsburgh. He gave up two runs and four hits while striking out a career-high 14 in seven innings of a 5-2 victory in his first major league start June 8, 2010. He then finished with 13 strikeouts and allowed one earned run in six innings of a 4-2 win May 10.Washington, though, has dropped four of six after falling 3-1 to the Pirates in Friday's series opener. Danny Espinosa had an RBI single but Ryan Zimmerman went 0 for 4 in his return to the lineup after missing 14 games with a strained left hamstring.The Nationals have scored three runs or fewer in six straight games."I don't know if it's being aggressive early in the count or not, but I do feel we're trying too hard to make things happen," Johnson said. "Everyone just needs to relax a little bit."Andrew McCutchen has been hitting much better lately for Pittsburgh (17-12), which improved to 16-7 since starting the season 1-5. McCutchen went 3 for 4 with a solo homer Friday and is 8 for 17 with two homers and four RBIs over his last four contests to bump his average up 41 points to .257.The Pirates, who have taken five of the last seven meetings with the Nationals, will look to win a fifth straight home game as they send Jeff Locke to the mound.Locke (3-1, 2.83) got off to a rocky start but has been stellar over his last two outings while extending his scoreless streak to 13 innings. He allowed two hits and struck out six in six innings of a 2-0 win over Philadelphia on April 23, then gave up three hits in seven innings of a 9-0 victory over St. Louis on Sunday."Locke pitched a great game (Sunday)," catcher Russell Martin told the team's official website. "Getting my pitcher putting up scoreless innings gets us in a place to win."The left-hander, who had one victory in 10 career starts entering this season, has never faced the Nationals nor any hitter currently on their roster.