The Nationals scored five runs in the eighth, including four off the struggling Kolb, and backup catcher Gary Bennett had a career-high five RBI to lead Washington to an 8-6 victory over Atlanta on Thursday night.
Kolb (1-5) entered in the bottom of the eighth with a 6-3 lead after the Braves had rallied for four runs in the top of the inning. He gave way to Kevin Gryboski after recording just one out, leaving with the score 6-5 and runners on second and third.
After Gryboski intentionally walked Marlon Byrd to load the bases, Bennett doubled into right-center field to score all three runners.
"I pretty much feel terrible about my whole season right now," said Kolb, whose ERA is now 7.29. "Go home, do some thinking and see what happens tomorrow."
Bennett's go-ahead hit came after he gave the Nationals a 2-0 lead in the second with his first home run of the season, a two-run shot.
"He got us off to a good start today, and he put a good finish on it at the end," Nationals manager Frank Robinson said.
The loss dropped the Braves percentage points behind first-place Florida in the NL East, with Washington 1½ games back.
"You sure hate to lose it after you after you come back like that, haven't been hitting a whole bunch and get four runs and then give five up right away," Braves manager Bobby Cox said.
Robinson, on the other hand, said the victory was huge for the Nationals, who won three of the four games in the series.
"This was a big, big, big ballgame," he said. "It's the type of game you can get some momentum on."
The Nationals got started in the eighth when Carlos Baerga pulled a grounder through the right side of the infield to score Jamey Carroll, followed by Vinny Castilla's RBI double that cut Atlanta's lead to 6-5 and chased Kolb.
Washington reliever Gary Majewski, who had made 11 straight appearances without giving up a run, inherited a 3-2 lead in the eighth but couldn't hold it. Andruw Jones tied it with a one-out sacrifice fly. The Braves then loaded the bases, and all three runners scored after a single by pinch-hitter Johnny Estrada.
Estrada, after falling behind 0-2 in the count, fouled off three straight pitches before hitting a grounder up the middle past Majewski. All three runners scored on the play after a throwing error by center fielder Brad Wilkerson, who had tried to throw out Wilson Betemit at third.
Hector Carrasco (2-1) replaced Majewski and got the final out of the eighth before Chad Cordero pitched the ninth for his 14th save in 16 chances.
The Nationals blew a two-run lead Wednesday night against the Braves, giving up three runs in the eighth and losing 5-4. That came after Washington posted three consecutive one-run victories.
Washington received another good start by Esteban Loaiza, who allowed two runs and five hits over six innings, striking out seven. He is 1-4 despite a respectable 3.61 ERA. The Nationals average 1.9 runs when Loaiza is in the game, the worst run support in the majors for any starting pitcher.
Loaiza helped his own cause leading off the fifth with a double, moving to third on Wilkerson's groundout, and scoring on Carroll's sacrifice fly when a poor throw by right fielder Brian Jordan allowed the slow-footed Loaiza to trot in just ahead of the tag.
Loaiza pitched his way out of a jam in the sixth. After a one-out RBI single by Adam LaRoche made it 3-2 with runners on first and second, Loaiza struck out Andruw Jones and Jordan in succession to end the inning.
Nationals 1B Johnson left the game after seven innings, complaining of chest pains. He was later diagnosed with stomach reflux. ... Nationals 3B Castilla ground into double plays in the third and sixth innings. ... Pena's groundout RBI in the fifth was the first of his career. He was playing in only his fourth game of the year. ... The Nationals twice had runners picked off late in the game, Byrd in the sixth and Cristian Guzman in the seventh.