SAN FRANCISCO -- Two teams that would be National League first-round playoff opponents square off Thursday night in the opener of a four-game series that will feature neither team's staff ace.

The Washington Nationals and San Francisco Giants will take identical 59-42 records onto the field for the first of seven games they will play coast to coast over the next 11 days.

The Nationals, who lead the NL East by four games over the Miami Marlins, rode ace Stephen Strasburg's strong seven-inning outing to a 4-1 win over the Cleveland Indians on Wednesday before boarding a flight to San Francisco.

The Giants, meanwhile, retained a 2 1/2-game lead in the NL West despite a 2-1 loss to the Cincinnati Reds, a game in which ace Madison Bumgarner lost despite allowing only two runs (one earned) in eight innings.

By virtue of both having pitched Wednesday, neither Strasburg nor Bumgarner is scheduled to start again until next week.

Interestingly, both are tentatively slated to pitch a week from Sunday, when the Giants and Nationals wrap up a three-game series in Washington.

Thursday's first 2016 meeting of the division leaders will pit Giants center Denard Span against his former team for the first time since he left as a free agent over the winter.

Washington might finally have found an adequate replacement atop the batting order in Trea Turner, the offensive star the Wednesday win with three hits and three RBIs.

He is batting .297 in eight games as the Nationals' leadoff hitter after the earlier Span replacements struggled at a .214 clip.

"He's fun to watch," Strasburg said of Turner after Wednesday's game. "I was just excited the other day to finally watch him hit a triple. I was waiting for that for such a long time, just to see him run."

The Nationals will be catching Span in his hottest stretch of the season. The Giants leadoff man has recorded two more hits in nine of his past 16 games, raising his average to .256.

The Nationals will begin the San Francisco portion of the seven-game sequence by sending right-hander Tanner Roark to the mound.

Roark has been roughed up on a regular basis over his past nine starts, allowing four or more runs on four different occasions, including in his last outing against the San Diego Padres.

Roark gave up a pair of home runs among four hits in five innings against the Padres, allowing all San Diego's scoring in 5-3 Washington loss last Friday.

Home runs were plentiful in the Giants' just-completed series with the Cincinnati Reds, during which San Francisco pitchers allowed eight long balls in three games.

That was the most home runs allowed by the Giants in a three-game series in AT&T Park history.

The homers led directly to a pair of Reds wins, which dropped San Francisco's record since the All-Star break to 2-9.

"We've been through this plenty of times, and we know what it's about," Bumgarner said of the Giants' struggles of late. "Things will turn around for us."

Right-hander Johnny Cueto (13-2) gets the call for the Giants on Thursday. In his most recent outing, he allowed one run, which was unearned, in six innings Saturday during a no-decision against the Yankees at New York. San Francisco won 2-1 in 12 innings.

Outside of the pitching matchups, second base will be a position of focus in the weekend series.

Nationals second baseman Daniel Murphy smacked his 20th home run of the season in the series finale against Cleveland. He will take the field Thursday with the NL's best batting average (.354).

The Giants, meanwhile, have gone 23 games without their star second baseman, Joe Panik, who is recovering from a concussion. San Francisco has gone just 10-13 during that stretch.

Panik began a rehab stint at Triple-A Sacramento earlier this week, and Giants manager Bruce Bochy hopes to have his 2015 All-Star, a .300 hitter in each of the previous two seasons, back in the lineup by the weekend.

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