Two errors later, Rosario was right back where he started - though it took him a couple seconds to get up while catching his breath following a slide into home plate.
Colorado scored three runs during that wild fifth-inning sequence and pounded starter Yovani Gallardo to avoid a season sweep to the Brewers with a 10-4 victory Sunday.
"Yeah, it's a home run, that's a home run for Rosario," manager Walt Weiss said. "One of the turning points if not the turning point of the game."
Rosario took advantage of the gaffes with runners on first and second. His shot to third was booted by normally sure-handed third baseman Aramis Ramirez.
"No excuses. I should have made that play," Ramirez said.
One run had already scored when the ball squirted into foul territory. Shortstop Jeff Bianchi then threw home high and offline trying to get Corey Dickerson. Good thing Dickerson actually didn't heed third-base coach Stu Cole's advice to stay put.
"But I kind of noticed (Bianchi) was pretty far away to be able to make the throw, so I took off and slid," Dickerson said. "That's when I got the strawberry (on his left leg), so I really didn't pay attention after that. So I really didn't know what happened behind me."
That would be the 220-pound Rosario chugging home safely for a six-run lead after catcher Jonathan Lucroy threw errantly attempting to get Rosario at third. Wearing dark sunglasses, Brewers manager Ron Roenicke watched calmly in the dugout with arms crossed what he later called the "meltdown."
The Rockies pounced on a team that looked a little tired after wrapping up a stretch of 20 games in 20 days, though Roenicke wasn't sure if fatigue may have played a role in the field in the fifth.
"You can have those plays any time," Roenicke said. "You get down when you see it, so it's hard to bounce back after a play like that."
Jorge De La Rosa (8-6) got the win despite allowing three wild pitches and hitting one batter. Gallardo (5-5) was tagged for 10 hits in five innings.
The Rockies had jumped on Gallardo for a 5-0 lead through three innings - quite an accomplishment after the right-hander had allowed just three in his previous four starts combined. Colorado snapped a six-game slide to Milwaukee in the clubs' last meeting of the regular season.
Ryan Braun slugged an opposite-field solo shot into the Rockies bullpen in right for his 11th homer of the year. Braun also doubled in the sixth and scored on one of two wild pitches by De La Rosa in the inning.
"Those wild pitches I (made), that cost some runs, De La Rosa said. "But the most important thing, we win."
Khris Davis' RBI groundout later in the sixth made it 8-4 when Ramirez scored following a steal of third. Ramirez, 36, stole two bases in a game for the first time in his 17-year career.
It could have been much closer if not for the Milwaukee miscues in the fifth that had the National League's best team resembling a Little League outfit.
As for Colorado, maybe this victory will snap the team out of a June funk. The Rockies had lost four straight entering Sunday, as well as 11 of 12.
De La Rosa allowed four hits, two walks and four runs in six innings.
NOTES: Dickerson said he would be fine after leaving with a left hamstring cramp following a 1-1 count in the eighth after fouling off a pitch. ... The Rockies want 3B Nolan Arenado to get about 25 at-bats in a rehab assignment with Triple-A Colorado Springs before returning to the lineup. Arenado has been on the disabled list since May 24 after breaking his left middle finger on a head-first slide into second in Atlanta. He started the rehab assignment Saturday. ... Roenicke hoped to get OF Carlos Gomez (neck strain) and SS Jean Segura (left quad) back for the start of a two-day interleague series Tuesday at Toronto. RH Marco Estrada (7-4) is scheduled to get the start. ... LHP Yohan Flande (0-0) will make his second career start when Colorado opens a three-game series Monday in Washington.