Span was dropped from the top spot in the order for the first time this season, and he responded with three hits in the No. 7 position, including a tiebreaking two-out RBI double in the 10th inning to help beat the Miami Marlins 5-2.
Span snapped a 1-for-20 slump with a two-out RBI double in the second inning, and singled in the fourth. The three hits raised his average to .260 and helped the Nationals head into the All-Star break at 48-47.
"I just said, 'Hey, I'm going to try end this first half on a good note,'" Span said. "I couldn't play any worse than I have this first half. I just wanted to go out feeling good. I didn't want to go home feeling in more of a stale mood than I'm already in."
It has been a frustrating season so far for Span and the defending NL East champions, who averted a series sweep and snapped a three-game losing streak. They went 2-4 on their trip and trail division leader Atlanta by six games.
"I like this ballclub," manager Davey Johnson said. "We've had few hiccups with injuries and whatever, but I think we're in good shape going into the second half. We're an awfully good ballclub, and we just need to play like it."
On Friday, the Nationals begin their longest homestand of the season -- 11 games.
They salvaged the series finale at Miami despite going 2 for 10 with runners in scoring position, and hit .087 (4 for 46) in those situations during their trip. They had four hits without scoring in the fourth inning, when right fielder Giancarlo Stanton threw out two base runners.
Bryce Harper replaced Span in the leadoff spot, batting there for the first time in his career, and went 1 for 5 with a double and a walk. Jayson Werth, Ian Desmond and Anthony Rendon each had two of Washington's 14 hits.
"We hit a bunch of balls hard, and I like the way it felt," Johnson said. "Everybody seemed to have a little energy in the new lineup, and I'll probably stick with it more."
Harper was pleased with Johnson's decision to bat him first.
"I loved it. I really did," he said. "Getting the ABs I did, five or six ABs, that was pretty awesome. I like doing it. I did it in high school. It was pretty cool. If he left it there, I would be absolutely comfortable."
With the score 2-all, Werth hit a one-out single in the 10th off Steve Cishek (3-5), and Span hit a double that landed on the warning track in center field to give the Nationals the lead. That ended Cishek's streak of 16 1/3 consecutive scoreless innings, the longest active streak in the major leagues.
"I flipped in a couple of lazy sliders that killed me," Cishek said. "I really wanted to finish on a strong note for the first half. Sweeping the Nationals would have been great."
Washington rookie Taylor Jordan remained winless in four career starts despite an ERA of 3.32. The Florida native allowed two runs in six innings before departing for a pinch-hitter.
Miami snapped the Nationals' franchise-record streak of hitting a home run in 86 consecutive series. Derek Dietrich hit a two-run homer for the Marlins, his ninth, but they squandered several scoring chances.
A line drive by Dietrich along the right-field line was initially ruled fair by first-base umpire Mike Estabrook, putting runners at second and third with none out in the second inning. But plate umpire Alan Porter reversed the call, Dietrich struck out and the Marlins didn't score. TV replays were inconclusive.
Miami LHP Duane Below was optioned to Triple-A New Orleans. RHP Chad Qualls will be placed on the paternity list. ... Werth fouled a ball off the top of his left foot and left the game in the 10th. He was limping after the game and said he was unsure whether he might miss any playing time when the season resumes. ... Washington RHP Tyler Clippard struck out the side in the ninth. In his past nine innings, he has allowed one hit with 11 strikeouts. ... Miami SS Adeiny Hechavarria had two hits and is batting .412 (21 for 51) this month. ... Marlins C Jeff Mathis has thrown out 13 of 18 runners on steal attempts.