Both times, Lee was in the middle of the action. He hit a potential double-play grounder that instead scored two runs, thanks to Weeks' ninth error, and then a tie-breaking double in Chicago's two-run ninth inning against Torres (5-3).
"In games like this, there's so much energy and you've got two pretty well-matched teams playing in front of a crowd like that, it's fun," Brewers manager Ned Yost said. "But the team that makes the least amount of mistakes is probably going to win.
"You have to make the opposition earn it by hitting their way on, not walking guys and having defensive miscues in the field. That's what ended up getting us tonight."
Not before both teams thrilled a sellout crowd of 45,311, the largest this season and third-largest in the Brewers' eight seasons at Miller Park.
Cubs reliever Chad Gaudin (2-1) struck out the side in the eighth for the win and Carlos Marmol was electric in the ninth on the way to his fifth save. At 62-44, the Cubs moved two games ahead of the second-place Brewers.
CC Sabathia started for Milwaukee and saw his streak of three consecutive complete games come to an end despite a 124-pitch performance, the third-highest total of his career. Lee put the visitors on the board with a first-inning single that scored Alfonso Soriano, who made it 2-0 in the third with a solo home run.
The Brewers snuffed out a Cubs rally in the sixth inning, when center fielder Mike Cameron threw out Lee at home plate and Brewers first baseman Prince Fielder made a diving stop and shoveled to Sabathia for the final out. Those plays put the Brewers in position to take a 3-2 lead in the bottom of the sixth. Hardy and Braun hit back-to-back home runs off Cubs starter Ted Lilly, Fielder followed with a single and then chugged all the way home on Corey Hart's double to left-center field.
"Obviously, it's not fun to come out on the wrong end of that game, but we just have to regroup," Braun said. "That loss isn't any more significant than any other. You just come back [Tuesday], and we've got Ben Sheets going, so I like our chances."
Back came Chicago in the top of the seventh with some help from Weeks. Ronny Cedeno opened the inning with a single and advanced on an infield hit by pinch-hitter Kosuke Fukudome to Weeks, who couldn't make a tough, backhanded play.
Sabathia appeared to catch a break when he struck out Soriano while both runners broke from their bases. Catcher Jason Kendall's throw was well ahead of the lead runner Cedeno, but it also beat Brewers third baseman Bill Hall to the bag, and the call from third-base umpire Doug Eddings was safe, despite Yost's protest.
Reed Johnson walked to force a bases-loaded showdown between Sabathia and Lee, and the lefty appeared to win it. Lee hit a bouncer to Hardy at shortstop, who fed to Weeks for the second out. But Weeks' throw was way wide of first base as the second run scored for a 4-3 Chicago lead.
"It's a double play that has to be made," Yost said. "What happens is, sometimes he tries to be too quick."
Weeks made no excuses.
"I tried to turn it the best way possible," Weeks said. "It just got away from me. ... It's not a mental thing, it's going out there and making a play. I made a mistake. I haven't had too many of those in clutch situations. That's the way it goes."
Pinch-hitter Branyan, hitting .150 since his last home run on June 27, recharged the crowd in the bottom of the seventh when he tied the game at 4 with an opposite-field home run off Bob Howry.
The score remained knotted into the ninth, when Torres struck out Fukudome leading off the inning. He was ahead of each of the next two hitters, 1-2, but walked both Soriano and Mike Fontenot to bring up Lee, who deposited a sinker into right field for a double and a 5-4 Cubs lead. Mark DeRosa added an RBI infield hit that scored Fontenot.
"I know exactly what I did wrong," Torres said. "Unfortunately, you are always aware of that after the game is over. It seemed like I was 1-2 on every hitter, but they were patient late in the count and I was not able to detect that.
"I feel like I let them off the hook. I had them in pitchers' counts there."
Yost was obviously upset. He also appreciated the drama of the night.
"My only instinct after the game was, 'Wow,'" Yost said. "It was so much fun being in a game in the end of July with that much intensity, that much action, that much excitement and electricity. I was thinking in the sixth inning that this was so good for our players to go through something like this at the end of July to get them a sense to play deep, deep into the season.
"This was all of that. I've been through a lot of playoff games, a lot of World Series games, and seen the intensity of the crowd. This matched it ... tonight."