The final two months of the Washington Nationals’ season promise electric nights and marquee showdowns, the type of games that attend meaningful baseball in fall. The coming week, starting with two games Friday, promises the opposite. The Nationals will face two teams already staring into winter, the dregs during the dog days, opponents made for fattening up on.

By Friday night, the beginning of the Nationals’ record-padding opportunity had gone to plan. They had a 7-4 victory over the Miami Marlins in Game 1 in their back pocket, an immediate lead in Game 2 and Gio Gonzalez cruising on the mound. Suddenly, the Nationals had to settle for a split as Josh Johnson’s near-complete game and the Marlins’ pop-up rally foiled them in a 5-2 loss in the nightcap, even as Gonzalez pitched a season-high eight innings.

The Marlins may be miles from contention, but these are still critical games for Washington. The Nationals play Miami four times, followed by four against the Houston Astros. Both opponents were bad before they disintegrated with a series of trades. The Nationals have an ideal chance to build on their lead over the Atlanta Braves in the NL East, which sits at two games after the split and a Braves win.

Taking advantage requires constant alertness, and Manager Davey Johnson was alarmed by one moment nearly every observer would have missed. During Game 1, the Nationals led 7-1 in the sixth inning, and Marlins infielders played behind Jayson Werth at first base, conceding a steal. Werth, in compliance with standard etiquette, stayed.

“I was a little upset when we didn’t run,” Johnson said. “You don’t quit competing. You don’t let them dictate when they’re out of it, because they’re going to keep competing. I had a few discussions – ‘Why didn’t we run?’ Those are little things. But they can be big things. It doesn’t matter who you’re playing. You’ve got to be at your best.”

For most of Game 1, the Nationals were. John Lannan made his second cameo from the minors and turned in six solid innings, his second victory in as many major league starts. (”It was a little less weird” than the first time, he said.) Adam LaRoche continued a torrid stretch by going 3 for 4 with a homer. Both he and Mark DeRosa drove in three runs. Even with Bryce Harper and Michael Morse taking a rest, the 3-4-5 hitters — Ryan Zimmerman, Werth and LaRoche — reached base in 12 of 15 plate appearances.

“The healthier we get, the better we’re going to be,” Zimmerman said.

The Nationals stranded 11 runners, and shaky relief pitching necessitated Johnson summoning closer Tyler Clippard when he did not want to. He worried about the tax on his bullpen with a game to go. But the Nationals had controlled the entire game, and it lasted into the beginning of Game 2.

Steve Lombardozzi led off against Johnson with a triple to the center field fence, and two batters later Zimmerman scored him with a sacrifice fly to right field. The Nationals led, 1-0.

Gonzalez was sublime for his first five innings. Jose Reyes reached on a bunt single with two outs in the first, and then Gonzalez retired 12 of the next 13 batters he faced. He struck out five of them. He allowed a single to Greg Dobbs in the fifth, and on the next pitch Austin Kearns grounded into a rocking-chair double play. Gonzalez needed 49 pitches for five innings, 36 of them fastballs.

Johnson roped a single into the corner with one out in the sixth inning, only a blip. With two outs, the Marlins suddenly burst out. They sent flares into the outfield and grounders through the infield. Four consecutive two-out singles sent them ahead, 3-1. In a flash, Gonzalez’s brilliance had been reduced to rubble.

“I got the groundballs that I wanted,” Gonzalez said. “It’s just, they found holes.”

He hurled another two innings, saving the bullpen and compiling a mostly dominant box score. Gonzalez became the only Washington starter other than Edwin Jackson to pitch past the seventh this year. He struck out 10 and walked none.

The frustration of pitching so well in a lost cause spilled over for Gonzalez in the eighth. Reyes doubled to right field with one out and Carlos Lee followed with a routine grounder to shortstop Danny Espinosa. Reyes was running on the pitch, and as Espinosa cocked to throw, he kept running around the third base bag.

“Danny should have seen that coming,” Johnson said.

Instead, he fired to first and Reyes beat LaRoche’s throw home with ease. Gonzalez yelled in Espinosa’s direction, motioned toward the plate, took his glove off his right hand and slammed it against the turf.

The Marlins led, 4-1, and with Johnson on the mound the Nationals stood little chance. Only three Nationals reached base against him between the second batter of the game and the start of the ninth inning. He allowed five hits and struck out nine in 8 2/3 innings.

“Obviously, their records aren’t as good as ours, but these teams have talented guys on them,” Zimmerman said. “When they have a guy like they threw tonight, it doesn’t matter if they’re 20 or 30 games under .500. You got to beat that guy that day.”

The Nationals (63-43) could at least fall back on their Game 1 victory. Lannan joined the Nationals from Class AAA Syracuse, where he has spent his season exiled by the Nationals’ high-powered collection of arms. He last started for Washington in the back half a of a doubleheader two weeks prior, when he fired seven masterful innings for a crucial win over the Braves.

“He’s been outstanding,” Johnson said. “He’s been a big boost. He’s had a rough year, going up and down. But he’ll be back up here soon.”

Friday afternoon, like his start against the Braves, Lannan stumbled through the first inning. The first three batters reached base, but he induced a 6-4-3 double play and escaped allowing only one run.

Over the next five innings, he faced two batters over the minimum. He walked five hitters and didn’t retire any of the three hitters he faced in the seventh. Lannan gave the Nationals more confidence that he can fill in for Stephen Strasburg in September, whenever the ace gets shut down.

“I wish I could stay up here, but I know the deal,” Lannan said. “I got to go back down there and keep on working.”

The Nationals had won one game, which for the next week is what they are supposed to do.

“It could have been better, but we’re all still alive,” LaRoche said. “So we’ll get them tomorrow.”