Close calls haven't gone in the Cubs' favor much over the last few months, but this one led directly to a 4-2 victory over Milwaukee. Two batters later, Corey Patterson delivered a two-out, two-run homer off Luis Vizcaino.
"In my mind we're owed a lot more breaks," manager Dusty Baker said. "We haven't had hardly any breaks. If they even out, boy, we have a lot coming."
Grudzielanek's controversial double and right fielder Brady Clark's subsequent throwing error on the play put Grudzielanek on third and set the stage for Patterson's heroics that gave the Cubs their fourth straight victory and their seventh in the last eight games.
They moved a season-high 14 games over the .500 mark and held on to their one-game lead over San Francisco in the NL wild-card race.
Greg Maddux was denied the victory despite allowing one run on four hits in eight innings. He threw just 84 pitches.
Another wild ending at Wrigley saw Moises Alou hit a homer off Vizcaino in the eighth to put the Cubs ahead 2-1. But Chris Magruder tied it in the ninth against closer LaTroy Hawkins with a two-out RBI double off the right-field wall.
Hawkins (3-4) was booed off the field at the end of the inning, but was credited with the victory after Patterson's blast.
Grudzielanek started the inning with an opposite-field fly ball that curved into the right-field corner, where Wegner ruled it hit the foul line before bouncing off the wall.
"It was coming down, the wind was blowing it back into fair territory, so it was definitely a close ball," Grudzielanek said.
After watching a replay, Wegner believed he was vindicated.
"It hit the line," he said. "That's why I'm on the line and I got a good look at itso fair ball."
Milwaukee manager Ned Yost said Wegner missed the play and was ejected for arguing the call.
"I don't know what line he was talking about," Yost said.
With Grudzielanek on third, Paul Bako and pinch-hitter Todd Walker both popped out. But Patterson took a 2-2 pitch and launched it into the no-beer section in right field for his 18th homer, igniting a celebration scene at home plate.
Bako, who hit his first home run in more than two years in the fifth, credited a team meeting Baker called last week for the Cubs' hot streak.
"We got a lot of things ironed out," he said. "We're playing great baseball since then, no doubt. We're just concentrating a little more, each inning and each out."
Baker, who is not big on team meetings, declined to discuss what he said in this one.
"Sometimes they work," he shrugged. "We had a team meeting at the beginning of the year and lost three in a row, so I was apprehensive about this one."
Patterson, the team's hottest hitter in August, said everything revolves around a positive approach.
"It's pretty simple," he said. "If you think good things are going to happen, nine out of 10 times it's probably going to happen. But if you're always worried, 'I'm not sure about this or that,' then you're not focused on what's going on.
"Baseball is a game of inches and split seconds, and it's going to be too late."
Hitting coach Gary Matthews, assistant coach Sonny Jackson and third-base coach Wendell Kim have helped Patterson turn things around in extraordinary fashion.
He's hitting .387 in 21 games since moving into the leadoff spot on Aug. 1, with eight doubles, seven home runs and 15 RBIs. He's playing center field like Curt Flood in his prime.
"They worked me pretty hard this year," Patterson said. "That's what I had to do, because at the beginning of the year I wasn't a really good ballplayer, in my mind. They saw that. It was starting to snowball.
"The guys sat down with me and said, 'Look, this is what you need to go back to doing and we'll be with you all the way through the end of the season.'
"They have, and things have paid off."