Game 40 lineups: Nats at Diamondbacks

PHOENIX - It was only a few weeks ago when the Nationals kept needing Max Scherzer to be their stopper and put an end to losing streaks. Now they just want their ace to keep the team rolling while it's playing some exceptional baseball.

Tonight the Nationals seek their 11th win in 13 games, a sustained hot streak that has allowed them to move from five games under the .500 mark to three games over. And who better to have on the mound than Scherzer, who comes into this game 6-1 with a 1.74 ERA and a league-leading 80 strikeouts in 51 2/3 innings. The right-hander did not face this good Diamondbacks lineup last month in D.C., so this will present a good challenge for him.

Speaking of challenges ... Arizona's starter, Matt Koch, has been thrust into a most difficult situation of late. Tonight marks his third consecutive outing against a former Cy Young Award winner. First it was Clayton Kershaw. Then it was Justin Verlander. Now it's Scherzer. The Diamondbacks, for what it's worth, won those first two matchups.

Davey Martinez's lineup has a new wrinkle: Bryce Harper has been dropped from the leadoff spot and moved into the No. 2 position, with Trea Turner bumped up to the No. 1 spot. It's a move that seemed forthcoming for a few days now; Martinez finally decided to go through with it. Ryan Zimmerman also notably is absent for the second straight night. He was dealing with a sore back yesterday, though he did prepare to pinch-hit late in case he was needed.

No official announcement yet on Matt Wieters, but the veteran catcher is being placed on the disabled list, and Spencer Kieboom has been called up from Triple-A Syracuse to back up new No. 1 catcher Pedro Severino.

WASHINGTON NATIONALS at ARIZONA DIAMONDBACKS
Where: Chase Field
Gametime: 9:40 p.m. EDT
TV: MASN2, MLB.tv
Radio: 99.1 FM, MLB.com
Weather: Indoors

NATIONALS
SS Trea Turner
RF Bryce Harper
3B Anthony Rendon
1B Matt Adams
LF Andrew Stevenson
CF Michael A. Taylor
C Pedro Severino
RHP Max Scherzer
2B Wilmer Difo

DIAMONDBACKS
LF David Peralta
CF Jarrod Dyson
1B Paul Goldschmidt
3B Daniel Descalso
RF Chris Owings
C Alex Avila
2B Ketel Marte
SS Nick Ahmed
RHP Matt Koch