Niemann tossed six scoreless innings in his return from a back injury and the Rays beat the Milwaukee Brewers 8-4 on Monday night in their first-ever appearance at Miller Park.
"To pitch that well really gets you going in the right direction, no question about that. You're always going to have those negative thoughts in the back of your head that you've got to squash somehow," Rays manager Joe Maddon said. "I'd like to believe what he did tonight is going to bolster his confidence a bit and get him ready for the next outing."
Niemann (2-4) was on the disabled list for 45 days with a strained lower back, but he said it felt fine Monday night and he looked comfortable while using his big curveball to hold the Brewers to four hits while striking out five.
"Everything felt great," Niemann said. "The biggest thing is it's just nice to be back and be in this clubhouse and be a contributing member of the team again. That was the hardest thing while I was down on the DL, they've been playing great and it was good to chip in."
"They're tough to beat at home," Longoria said. "To get Game 1 out of the way and get a win is a big momentum boost being here and moving forward."
Jonathan Lucroy homered for Milwaukee, which was without left fielder Ryan Braun because of a respiratory infection. The Brewers fell a half-game out of first place in the NL Central, trailing the idle Cardinals.
The Rays have won four straight and 10 of 14, but this one was in doubt until the seventh.
With Tampa Bay clinging to a 1-0 lead, Kelly Shoppach walked, reached second on a sacrifice and scored on pinch-hitter Jason Ruggiano's double.
Longoria connected against Mark DiFelice for his sixth homer, making it 8-1. The All-Star third baseman began the day in a 2-for-24 rut that dropped his June batting average to .196.
"After the series I had at home where I hit four or five balls hard right at guys, sometimes you need those to get going," said Longoria, who believed his homer would've been a routine out at Tropicana Field.
Maddon isn't concerned with Longoria's lack of offense.
"He's going to get hot, real hot," Maddon said. "He's a definite grinder. You will never hear an excuse out of his mouth. He holds himself to high standards."
Leading by seven, Maddon let outfielder Sam Fuld, who had entered in the pitcher's spot as a pinch hitter, warm up on the mound before the eighth. Reliever Cesar Ramos then came in and allowed two runs to make it 8-3.
"I wasn't quite sure what the heck I was doing out there," said Fuld, who hasn't pitched in a game since his junior year of high school. "This is like a position player's dream in a lot of ways. I looked up at the radar, I didn't get a reading. I was thinking, just don't get hurt."
Milwaukee remains a majors-best 25-10 at home, but have lost six of eight since sweeping the Cardinals out of first place just over a week ago.
The Brewers started coming unglued in the sixth inning.
Trailing 1-0, Nyjer Morgan was hit by a pitch, but ordered back to the box by plate umpire Bob Davidson. Morgan was incensed and had to be led away from Davidson. He calmed down enough to finish the at-bat, but struck out.
"He said that he threw his elbow out into the pitch," Brewers manager Ron Roenicke said.
After Morgan returned to the dugout, both Roenicke and hitting coach Dale Sveum were ejected.
"It was magnificent. He had really good stuff," Maddon said of Niemann's escape. "It was a really, really strong first day back."
The only other series between the clubs was at Tropicana Field in 2005. ... Rays RHP Alex Cobb was sent down after Sunday's game to make room for Niemann. ... Rays pitching coach Jim Hickey was not with the team after his home in Florida sustained significant damage in a fire. ... Brewers RHP Shaun Marcum (hip) may miss his next start with lingering soreness.