Pittsburgh (11-17) at Washington (12-17)

The Washington Nationals’ turnaround has helped improve the team’s confidence. They have felt particularly positive when John Lannan takes the mound.

Lannan looks to extend a 19-inning scoreless streak and help run the Nationals’ longest win streak of the season to five games when they continue their four-game series with the Pittsburgh Pirates on Friday night.

Washington (12-17) won the opener of this series 3-2 on Thursday night to give it four straight wins for the first time this season. Austin Kearns broke a tie with a two-out RBI single in the eighth inning to help give the Nationals their seventh win in nine games following a terrible first three weeks of April.

Washington now hands the ball to its top young pitcher. Lannan (2-2, 2.64 ERA) is 2-0 with a 0.45 ERA in his last three starts, striking out 18 in 20 innings.

The 23-year-old left-hander extended his scoreless streak to 19 innings Sunday with seven innings against Chicago in Washington’s 2-0 victory over the Chicago Cubs. He struck out three, walked four and didn’t allow a hit until Ronny Cedeno singled to start the fifth.

This will be Lannan’s first appearance against Pittsburgh (11-17).

The Nationals flip-flopped their starting pitchers for Games 2 and 3 of the series, deciding to give struggling left-hander Matt Chico an extra day to rest.

Pittsburgh, meanwhile, will be giving Phil Dumatrait (0-1, 3.92 ERA) his first start of the season after Matt Morris was released Sunday. Dumatrait, picked up from Cincinnati on waivers after last season, has pitched well in 10 relief appearances for the Pirates.

The left-hander made four starts for the Reds last season, walking 12 in 18 innings while posting a 15.00 ERA.

“He’s been in tough situations, and I think he’ll be ready to go,” Pirates manager John Russell told the team’s official Web site. “It’s a different year for him.”

Washington and Pittsburgh are starting left-handers in each of the first three games of this series. The last time three consecutive left-handers matched up was from Aug. 5-7, 1995 in a series between Atlanta and Montreal.

The Nationals managed just three runs against left-handers Zach Duke and John Grabow in the series opener. Washington has scored three runs or less in four of its last five games, but has won four of those contests.

Kearns was in a 2-for-29 slump (.069) before going 2-for-4 with a run scored Thursday, raising his average from .182 to .194.

“There’s so much more to Austin Kearns than the expectations that the outside world has put on him,” Washington manager Manny Acta said. “The expectations were, you know, 40 home runs, 120 RBIs, this and that, and I felt they were very high. I think a lot of people underestimate what Austin brings to our club.

“On the field, he’s one of the best in right field. He can field, he can throw, he’s accurate. He plays hard, no one can accuse him of lollygagging here, ever.”

The Pirates, meanwhile, managed only three hits in seven innings against Washington southpaw Odalis Perez, losing for the 11th time in 15 games after winning their previous four.

Pittsburgh struggled at the plate after scoring a season-high 13 runs in a win over the New York Mets on Wednesday.

Pirates second baseman Freddy Sanchez continues to show signs of breaking out of his early season slump, hitting his first home run Thursday. He is 5-for-15 with four RBIs in his last three games.