Vince Velasquez knew as he slid into third base on Tuesday night that a 5-4 loss to the Nationals was sealed. Velasquez, in the game as a pinch-runner after the Phillies used their four reserves, easily beat the throw from center field on a fly ball. The tying run, it seemed, was on third base with two outs in the ninth. The Phillies were rallying.

But Velasquez knew otherwise.

"I realized they were chanting," he said.

Velasquez left for third base too early as he started his sprint before Michael Taylor caught Jorge Alfaro's deep fly ball. The Nationals recovered the throw and immediately began pointing — and chanting — toward second base. Trea Turner threw to Wilmer Difo, who stepped on second. The game was over. The Phillies lost on a walk-off appeal. For a team that has suffered through its worst month of the season, this was new.

"He's not instructed to tag up there," Gabe Kapler said. "He's an inexperienced baserunner who gave us a very valiant effort just to go out there and be ready to run right there. He was prepared for that moment, he was anxious for that moment, ready for that moment and he just got a little overzealous. He and I just chatted about it. He understands that he can also score from second base on a base hit right there. It was just a pitcher — a very athletic pitcher — running the bases for us without much experience in that game situation."

The Phillies have lost eight of their last 10 games and 14 of their last 21. They have one just one of their last nine series. This loss was difficult, not only because of Velasquez's miscue but because of the team's failure to win a game when Aaron Nola outlasted Max Scherzer. They trail Atlanta by 4 1/2 games, their largest margin in the division since June 19. The Phillies have two games left before September, but the team seems ready to dive instead of climb as the season's final month nears.

"It's always painful," Nola said. "Right now, every loss is painful, to be honest with you."

The ninth-inning rally began when Nick Williams stroked a one-out double and Wilson Ramos followed by lining a ball down the right-field line to drive him in. Ramos, with both hamstrings ailing him, somehow powered himself to second base, beating the throw from right field. A night earlier, Kapler called Ramos "a warrior" for his willingness to play through pain. And it was that pain that forced the Phillies to remove him for Velasquez.

"I wasn't nervous at all. I just thought I wanted to put pressure on the outfield and I knew I had the base and I mean clearly the ball wasn't even there by the time I reached third base, so I knew I was capable of taking third," Velasquez said. "That's what happened at the end of the game. I left early and I can't do anything about it. I guess it was a simple base running mistake, but what can I do now?"

The Phillies were forced to rally after the bullpen wasted Nola's effort. Pat Neshek allowed a two-run homer in the ninth to Anthony Rendon, the first batter he faced after Bryce Harper drew a leadoff walk against Tommy Hunter. It was a crushing bullpen collapse on an evening when Nola outpitched Scherzer for the second time in five days.

"I know [observers] always say 'This is the worst one' every night, but I think everybody said that at the time that this is the worst. Which one is really the worst when you have 12 of them? It's tough," Neshek said. "I don't think anybody's really, 'Oh man, it's over.' It's not like that in here at all. If anything it's the opposite. People are putting it behind them and we're going to come out tomorrow. Nobody's really thinking about it."

Nola struck out eight in seven innings while allowing two runs, one of which was earned. The Nationals managed just four hits and did not have more than one runner on until the seventh inning. And that's when trouble came.

Nola allowed a double to Ryan Zimmerman to put runners on second and third, prompting Kapler to exit the dugout. Nola had exhausted 100 pitches on a humid night. But there was no decision to make; Nola was staying in.

Kapler returned to the dugout and Nola induced the next batter — Matt Wieters — to ground out sharply to first. Carlos Santana fielded it and touched first, but then misfired on his throw home to complete an inning-ending double play. The ball sailed high off  Alfaro and smacked the backstop. Two runs scored and an inning continued just when it looked to be finished. Those runs would be crucial when the bullpen eventually collapsed.

Nola's ERA (2.10) is the second-lowest in the National League and he will spend the season's final month in contention for the Cy Young Award. But none of that mattered on Tuesday.