After being questioned for their inability to break free from the rest of the National League East, the Washington Nationals are finally silencing their critics. The Nationals look to extend their season-high winning streak to seven games Monday when they begin a four-game set against the visiting Arizona Diamondbacks, who have lost five of their last seven. Washington is coming off back-to-back walk-off victories and stands six games ahead of second-place Atlanta in the National League East.The Diamondbacks have been out of contention for months, but rookie center fielder Ender Inciarte has capitalized on his opportunity and brings a 17-game hitting streak into Monday's contest. "He's a smart player and he utilizes his skills well," manager Kirk Gibson told reporters about Inciarte, who is batting .320 during his streak. "He plays hard." Washington right fielder Jayson Werth has been limited with a sore right shoulder, but he could return to the starting lineup Monday after providing a key double off the bench late in Sunday's win over Pittsburgh.TV: 7:05 p.m. ET, FSN Arizona, MASN (Washington)PITCHING MATCHUP: Diamondbacks LH Vidal Nuno (2-8, 4.92 ERA) vs. Nationals RH Jordan Zimmermann (8-5, 2.92)Nuno bounced back from a shaky outing against Kansas City by allowing two runs over 5 2/3 innings against Cleveland on Wednesday. The 27-year-old is 0-3 with a 3.92 ERA in seven starts since being acquired from the Yankees for Brandon McCarthy on July 6. Nuno, who is making his first career appearance against Washington, has yielded 20 home runs in 117 total innings this season.Zimmermann has posted four straight quality starts, including Wednesday when he held the Mets to one unearned run over 6 1/3 innings. The 28-year-old entered the month with a 3.94 career in August, but is 2-0 with a 1.37 ERA in three starts this season. Paul Goldschmidt has four hits in nine at-bats against Zimmermann, who is 2-2 with a 3.62 ERA in five career starts against Arizona, including a rough outing on May 12 when he allowed five runs in 5 2/3 innings.WALK-OFFS1. Diamondbacks 1B Mark Trumbo has reached base safely in 16 straight games.2. Washington CF Denard Span is has hit safely in 20 straight games at Nationals Park.3. Arizona is 15-26 in series openers this season.PREDICTION: Nationals 6, Diamondbacks 2