By the end of the next inning, Lee was on his way to the hospital with a ribcage injury that left Houston to deal with questions about when he'll be back on the field.
Houston manager Brad Mills is confident Lee will be able to build on Sunday's two-hit performance whenever he returns.
"He'll be OK," Mills said. "When he gets over this, he's going to come back and be fine. He had the two hits and the big home run which was nice. When he's healed, he'll pick up right where he left off and be fine."
Lee's home run, off Brewers starter Chris Narveson (1-2), came in the sixth and pushed Houston's lead to 4-0. That was the last at-bat of the day for Lee, who was injured in the seventh inning when teammate Angel Sanchez slid knee-first into his ribs while the two were going for Mark Kotsay's pop-fly double.
"He looked like he was in pain," Sanchez said of Lee after the collision. "Anytime you hit your ribs, I think it's really painful."
Lee was taken to the hospital for tests on the left side of his ribcage and was to spend Sunday night in the hospital. A chest X-ray did not reveal any rib fractures, but Lee was still scheduled to undergo a CT scan Sunday.
"He's going to take all kinds of tests and we'll find out more," Mills said. "When you have a collision like that, we're going to get everything checked out. It might feel like ribs on the surface, but it could be something else."
Norris struck out a season-high 11, allowed three hits and walked three in his longest outing of the season. He improved to 3-0 in five career starts against Milwaukee.
"He's done a real good job on his focus and concentration of what he's trying to get done, besides executing his pitches," Mills said of Norris.
It is the second consecutive game Milwaukee's offense has scuffled against the Astros after Wandy Rodriguez threw eight shutout innings in a 2-1 Houston win Saturday night.
"I don't know how many sliders he threw, but with the way it was working and he kept it down in the zone, there are not too many right-handed lineups that are going to get to it," Brewers manager Ron Roenicke said of Norris. "And yesterday, Wandy threw a great game against us, too. Hopefully we won't have too many of these stretches where we're not scoring."
Norris didn't allow a hit until Jonathan Lucroy singled to lead off the third inning. He sailed through that inning and until there was one out in the seventh, retiring 13 straight, with five strikeouts.
"I was in a groove," he said. "I was comfortable and the slider was really working for me today. I just threw a lot of strikes."
Milwaukee's next hit came when Prince Fielder singled a ball right at Norris that bounced off his upper arm and to third baseman Matt Downs. Trainers checked on Norris after he was hit, but he remained in the game after throwing a couple of warmup pitches.
He walked Lucroy to open the eighth inning before he was chased after walking Carlos Gomez with two outs. Norris appeared to be upset he was taken out, but exited to a standing ovation and was replaced by Fulchino.
"It was just one of those days where he was throwing all his pitches for strikes and he was on today," Milwaukee's Rickie Weeks said. "You can't do anything about it. The next time we face him, we are going to have to be ready."
Matt Downs reached on an error by McGehee before scoring on Jason Bourgeois' two-out single that made it 5-0 in the seventh. Bourgeois advanced to second on that play when reliever Sergio Mitre overthrew first base for an error. Sanchez grounded out to end that inning.
Bill Hall hit Houston's third consecutive single with no outs in the second inning to drive in a run and give Houston a 1-0 lead. Lee and Brett Wallace both singled to set up Hall's RBI, with Wallace extending his hitting streak to a career-high 10 games.
Humberto Quintero singled after the Brewers turned a double play, but Norris struck out to end the inning.
Narveson settled down after the second, facing the minimum in the third, fourth and fifth innings. He didn't allow another hit until Bourgeois singled with no outs in the sixth inning. Pence singled after that to set up Lee's shot.
Narveson yielded seven hits and four runs with seven strikeouts in six innings.