WASHINGTON — The Giants’ baseball marathon resumes with Sunday’s day game at Nationals Park, the second of three games in a 24-hour span.

That counts Saturday night’s series opener that was delayed 3 hours and started at 7:05 p.m. on the West Coast. The times for Sunday’s day-night double-header are 10:05 p.m. and 4:05 p.m.

It’s the Giants’ first twinbill since May 23, 205, when they split at Coors Field.

Their last sweep: April 23, 2012 against the Mets in New York.

The last time they got swept: June 1, 2013, at St. Louis.

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Chris Stratton is pitching Sunday’s opener, Matt Moore the nightccap. Stratton might wonder what it’s like to get a normal amount of notice before taking the mound.

His first start, he was a late sub for Johnny Cueto. His second, he filled in for Matt Cain. This time, he was scheduled to start Friday, but the game was rained out and Stratton was bumped two days so Jeff Samardzija could pitch Saturday on normal rest.

The Nationals are starting A.J. Cole in the opener and ace Max Scherzer in the nightcap.

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The Nationals received good news on the Bryce Harper front: No structural damage in his left knee, no ligament or tendon damage.

The All-Star right fielder, as a result of Saturday’s fall at first base and hyperextension of his leg, sustained a significant bone bruise on the inside portion of the knee.

Based on examinations and results of an MRI, the team said it’s possible Harper will play again this season, which prompted a sigh of relief throughout the clubhouse, front office and fan base. Everyone feared far worse.

Replacing Harper on the roster: Michael Taylor, who came off the disabled list.

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Both teams were able to call up a 26th player for the doubleheader, and both chose hitters over pitchers: Orlando Calixte for the Giants and Pedro Severino for the Nationals.

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Game 1 lineups:

Giants: 2B Panik, SS Crawford, LF Parker, 3B Sandoval, C Hundley, 1B Jones, RF Moncrief, CF Hernandez, RH Stratton.

Nationals: RF Goodwin, 2B Sanchez, 3B Rendon, 1B Zimmerman, LF Lind, SS Difo, CF Stevenson, C Lobaton, RH Cole.

John Shea is The San Francisco Chronicle’s national baseball writer. Email: jshea@sfchronicle.com Twitter: @JohnSheaHey