Pittsburgh (17-11) completed a sweep of St. Louis on Sunday as Nick Kingham, in his major league debut, retired the first 20 batters he faced and struck out nine Cardinals in a 5-0 victory at PNC Park.
The 26-year-old Kingham was perfect until Paul DeJong's two-out single in the seventh.
"I was nervous, yeah, no doubt. But it's good to be nervous. That means I care," Kingham told MLB.com. "That just made my intentions a little bit more heightened -- not more serious, but just handled everything a little more carefully."
The Central Division leaders got a two-run single from catcher Elias Diaz to break a 0-0 tie in a four-run sixth. Diaz is hitting .444 with a 1.167 OPS in 11 games.
The Washington Nationals (12-16) have been far from perfect of late, but did salvage the finale of their series with NL West-leading Arizona on Sunday.
One start after expressing frustration about an early hook, Gio Gonzalez (3-2) struck out eight over seven innings in a 3-1 win. Gonzalez threw a season-high 114 pitches after being removed one batter into the sixth inning last Monday at San Francisco.
Diamondbacks starter Robbie Ray was forced to leave with a strained right oblique muscle in the second inning, and Matt Wieters and Michael A. Taylor homered off reliever T.J. McFarland.
"I think we've played so many of those (close games), but it's nice to be able to see the win at the end as opposed to being on the other end," Wieters said.
The homer snapped an 0-for-12 slump by the Washington catcher, who began the day hitting an even .200 in a lineup that sorely needs another effective bat.
"I like my swing right now," Wieters said. "I do. I feel like I've hit some balls hard that I haven't really gotten anything for, but more than anything I'm staying focused on what we're working on, keeping it simple, keeping it easy, but also trying to take some good swings at some good pitches."
Nationals third baseman Anthony Rendon (bruised toe) took ground balls, ran and swung the bat Sunday. It is uncertain whether he will require a minor league rehabilitation assignment before rejoining the active roster.
Pittsburgh's Jameson Taillon (2-2, 4.91) opposes Tanner Roark (1-2, 3.77) in Monday's opener.
Taillon had an 0.89 ERA through his first three starts but has given up 12 runs on 14 hits in only 5 1/3 innings his last two times out.
In his last start, Taillon surrendered seven runs on 10 hits in 3 2/3 innings of 13-10 loss to the Tigers.
Taillon threw 57 strikes in 75 pitches, but the Tigers weren't missing.
"A lot of strikes. Stuff felt really good," he told MLB.com. "It seemed like the mistakes I made just got punished. At this level, you can't make mistakes."
Taillon is 0-0 with a 3.00 ERA in two starts versus the Nationals.
Roark gave up four runs on six hits over six innings in a loss to the Giants last time out. Though he hasn't won since April 2, opposing batters are hitting just .182 off Roark.
Roark is 2-1 with a 5.32 ERA in six games -- three starts -- versus the Pirates.
Starling Marte is 1-for-9 against Roark and Jordy Mercer is 2-for-6.
Ryan Zimmerman is 3-for-4 versus Taillon.