Nationals third baseman Anthony Rendon slides across home plate to score a run ahead of the tag by Miami Marlins catcher Jeff Mathis in the first inning at Nationals Park. (Geoff Burke/USA Today Sports)

If there is such thing as an ideal first game of a doubleheader — and many players these days would probably say there is not — it would be quick, well pitched and played under sunny skies. By those standards, the first game of the Washington Nationals’ day-night doubleheader was less than ideal.

The game began under bright blue skies, with Stephen Strasburg making his first start since his seven-year extension was announced. A first-inning rally gave Strasburg an early lead. It ended more than three hours later, in rain and gusting winds, after three Nationals relievers were forced into action to hold on for a 6-4 win , the Nationals’ third straight.

The streak did not extend to the nightcap. Tanner Roark struggled with his control, throwing 114 pitches — 67 for strikes — and exiting after five innings of a 7-1 loss. A lineup with four bench players mustered just five hits.

“Just gotta write it off as a bad second game,” Manager Dusty Baker said. “It’s very difficult to usually sweep a doubleheader.”

Roark allowed seven runs, including a towering third-inning home run to Westfield High and George Mason alum Justin Bour. Roark’s two walks in the fifth inning haunted him, leading to a four-run inning that put the Nationals in a six-run hole.

In the opener, Strasburg’s command was not as strong as usual. He needed 104 pitches to work through six innings, striking out seven and walking three to improve to 6-0. Marlins No. 3 hitter Christian Yelich hit a 1-0 fastball out to dead center in the first, the second extra-base hit Strasburg has allowed to a left-handed hitter all season. Yelich doubled home a run in the fifth, too, and now has more extra-base hits off Strasburg than the rest of baseball’s left-handed hitters combined.

“It was a grind out there today,” Strasburg said. “Kind of had some pitches for a little bit, and they kind of went away, so not my best, but you got to learn from it.”

Marlins starter Justin Nicolino, meanwhile, experienced an inauspicious beginning to his afternoon when he walked Michael A. Taylor, Anthony Rendon and Bryce Harper to start the first. Daniel Murphy and Ryan Zimmerman hit sacrifice flies to give the Nationals a 2-1 lead without a hit. Then Harper stole third, his sixth stolen base, equaling his total from his MVP season a year ago. Jayson Werth drove him home with a single through the left side for a 3-1 lead.

Taylor was the only non-regular to start the afternoon game. Ben Revere normally starts in center but never was likely to play more than one game Saturday, given that he returned from the disabled list just a week ago. With a right-hander pitching the nightcap, Baker chose Taylor against the left-handed Nicolino.

Taylor walked again in the second. Then he singled with one out in the fifth, stole second and scored on Rendon’s single. When Revere returned from his oblique strain, Baker acknowledged that Taylor had a chance to claim the starting job and didn’t take it with his up-and-down April. In his second start since Revere’s return, Taylor finished 2 for 3 with a double and reached base in four of five plate appearances.

“Michael Taylor, he’s a talent, big time,” Baker said. “That’s why we held on to him because we know the potential that he has and he can do more to win a game than just hitting.”

By the sixth, clouds had consumed a once-beautiful day, adding howling winds that left paper plates and plastic bags whipping around Nationals Park. Jeff Mathis singled to cut the Nationals’ lead to 4-3, and when Strasburg finished the inning his day was done.

Pitching coach Mike Maddux “always talks about, ‘How good are you on your worst day?’ ” Strasburg said.

“It’s not all lost when you’re not pitching well early on. Just keep pitching. Stay focused and do everything you can to put the guys in a position to go out there and win it.”

Rain began to fall in the bottom of the sixth, sending fans for shelter as Wilson Ramos hit his fourth homer — a line drive to left-center. One of the few fans unmoved by the rain caught it in the first row, forcing a review of whether he had reached over the wall and taken the ball out of play. Replay revealed he did not, and Ramos continued to stay hot — he has hit safely in 18 of 25 games and is batting .359.

After Felipe Rivero began the seventh by allowing back-to-back hits and a run, Shawn Kelley relieved him with one out and a man on, struck out Giancarlo Stanton, then got Bour to ground out. He pitched a scoreless eighth, too. Kelley has appeared in 17 games, has struck out 19 in 13⅓ innings and has not allowed a run.

“It was a little wet. I had a little issue with my footing,” Kelley said. “But I tried to just focus in and execute pitches, and I was able to do that when I got two strikes.”

Then came Jonathan Papelbon as puddles formed in the infield. He faced Stanton with the tying run on first and struck him out for his 11th save.

The Nationals had the option to add a 26th player to their roster Saturday and chose outfielder den Dekker over an extra reliever, likely knowing that Harper would drop the appeal of his one-game suspension and sit out the nightcap.

Before the second game, the Nationals retreated to the clubhouse for 2 1 / 2 hours. Roark put the Nationals in an early deficit, surrendering two runs on a triple, single and double in the second inning. Even though the Nationals loaded the bases in the bottom half against Marlins rookie Kendry Flores, who left an inning later with a shoulder strain, they couldn’t score.

The Marlins somehow cobbled together six innings with four relievers, and the Nationals managed just one run on a fourth-inning sacrifice fly by Stephen Drew. Murphy notched his 19th multi-hit game. The offense missed Harper, while Werth, Zimmerman and Danny Espinosa rested.

Sammy Solis relieved Roark and delivered three hitless innings, the lone bright spot of the night for the Nationals.