Ryan Zimmerman tumbles into Danny Espinosa after diving for home plate and scoring during the seventh inning. (Justin Edmonds/Getty Images)

The conditions at Coors Field, like mud on a horse track or dim lighting at a bar, can equalize mismatched contestants. High altitude and vast expanses of outfield grass ensure even the most motley outfit will stumble into one ripe opportunity, one chance to send a game-altering hit hurtling through the thin Rocky Mountain air.

Monday night, the teams with the best and worst records in the National League met on Blake Street. Before the Washington Nationals finished their 7-2 victory, the Colorado Rockies summoned a chance to topple them. Doug Fister had resisted, but the ballpark finally chewed him up with one out to go in the sixth inning. Manager Matt Williams trudged to the mound with the bases loaded, asked for the ball and gave it to Aaron Barrett.

"You're never out of a game here," Williams said. "And you're never comfortable here."

Barrett struck out Brandon Barnes with a slider from hell, which remained the night's key moment even after the Nationals added three insurance runs. The Nationals catapulted into first place and ran their NL-best record to 54-43, 11 games over .500 for the first time this season.

Ian Desmond became the third player in Nationals history to go 5 for 5, including a two-run homer off Rockies left-handed starter Franklin Morales that sparked a four-run fourth inning. Even he conceded the most important moment happened when Barrett relieved Fister.

"That was, in my eyes, the turning point of the game," Desmond said. "He did a great job."

Pivotal outs in a five-run victory, like the one the Nationals used Monday to surpass the Atlanta Braves, rarely happen in the sixth inning. Coors Field is different. It is an exhausting place to win even if the home team stinks. It finds ways to test teams, managers and pitching staffs even when the game seems squarely in their hands.

The test Monday night meant Barrett jogging in from the bullpen with the game hanging in the balance. Fister teetered in the sixth after five scoreless innings. He exited after he walked DJ LeMahieu, the No. 8 hitter, to load the bases with the Nationals clinging to a 4-2 lead. It didn't matter that the Rockies had lost five in a row or 44 of their last 62. They had a chance.   

"Anything's possible," Desmond said.

Somehow, none of Fister's 139 career starts had come at Coors Field. The ball travels further here, of course, but it also behaves differently when it leaves a pitcher's hand. Curveballs tend to hang. Two-seam fastballs, like the one Fister relies on, sink less. Livan Hernandez always hated Coors Field because it neutralized his guile. Fister figured it out, changing speeds and keeping fly balls in the park, before the Rockies scored two as they pounded five hits off him.

"There's definitely adjustments that needed to be made," Fister said. "Whether it's your curveball or your sinker, there's a little less movement. You've got to focus on location and let that override the movement."

As the Rockies rallied in the sixth, Fister suffered a minor twisted ankle trying to knock down a single up the middle from Carlos Gonzalez.  "I kind of tweaked it a little, but I'll be fine," Fister said. "It's one of those things that will be sore for a day or so, and it'll be right back to normal."

Fister yielded to Barrett, who faced Barnes, a hulking pinch hitter. Barrett, a rookie, had never pitched at altitude before. In the bullpen, his slider spun but wouldn't break. He told himself to stay with the pitch longer and focus on his follow through.

"I've been put in that spot a couple times this year," Barrett said. "But I think for me, it's about getting strike one, just attacking right out of the gate. Just try to keep a simple mind-set and go right after him." 

In tight spots, Barrett relies on that slider, the pitch that brought him to the majors back in spring training. It required him to place his trust in catcher Wilson Ramos. He wanted to bury it in the dirt, but if it scooted by Ramos, it would cost him a run.

In the first four pitches Barrett fired at Barnes, three were sliders, the last of which Barnes took in the dirt for a ball. Barrett went back to the same pitch, and this time Barnes flailed. Ramos blocked the pitch and stepped on home plate.

"It's a difference," Barrett said. "You can get timid on a certain pitch. You want to make a perfect pitch instead of having full confidence and just, 'Okay, I'm going to throw it in the dirt, and he's going to block it. No big deal.' "

The Nationals gave the rest of their bullpen a cushion. Ryan Zimmerman led off with a walk and Desmond pushed him to second with a single. When Ramos drilled a single to right, third base coach Bobby Henley windmilled Zimmerman home, which may or may not be the only action his right arm is capable of. Zimmerman tumbled to the dish as catcher Wilin Rosario muffed the tag.

"It felt like I fell off a motorcycle," Zimmerman said.

One batter later, Desmond scampered home to make it 6-2. In the ninth, Danny Espinosa mashed an RBI triple while batting from the left side to give the Nationals one added layer of protection.

The Nationals erupted in the fourth inning. Zimmerman led off and smoked a single to left field. Desmond fell behind, 1-2, and Morales tried to finish him off with a curveball, which against Desmond seemed like safe strategy. Last year, 13 of Desmond's 20 home runs came on offspeed pitches, but this season he hadn't belted a single curveball over the fence.

Morales's curve hung, though, and Desmond crushed it. The ball zoomed on a line over the left field fence. Desmond's 17th homer pushed the Nationals ahead, 2-0.

"I don't look for anything," Desmond said. "I just look for the ball and swing as hard as I can."

The barrage had just started. Wilson Ramos singled up the middle, then rambled all the home when Espinosa blasted a double off the base of the center field fence. Williams inserted Espinosa at second base for his defense behind Fister, who induces gobs of groundballs. Espinosa rewarded him with the RBI double, his first hit since June 22, a span of 27 at-bats.

"It was satisfying," Espinosa said. "It's fun to be part of the win when you make an impact."  

Fister followed Espinosa and tried to give the Rockies an out, pushing a bunt toward third base. Morales scooped the ball and looked toward third, but Espinosa's speed negated a play there. Morales whirled and fired a low throw to first that pulled Ben Paulsen off the bag. The Nationals still had no outs, and runners stood on first and third.

For reasons unknown to anyone in Coors Field, Morales tried to pick off Fister. The ball sailed off Paulsen's head and bounded down the right field fence. Espinosa trotted home, and Fister loped to third, now in possession of a 4-0 lead.  

It seemed like the Nationals would have an easy win, but those do not exist at Coors Field. The Nationals had to scrap, at least for a moment, and they did.

Nationals note: Kevin Frandsen turned his ankle during a pinch-hit at-bat in the ninth inning and hobbled to first base. Williams expected him to be sore, but did not think he suffered a significant injury. "It's a rolled ankle," Williams said. "We'll see how he is to treatment and see how he is tomorrow."