Three more runs scored when Anthony Brittain hit a two-run single and Steimel racked another RBI single.
Russel Havens scored Imperial's only run in the bottom of the fourth when he hit a home run.
"Imperial has a good squad," Tom Brittain said. "I expect to see them again."
Brittain said the productive second inning helped his team's confidence.
"We started playing Padre baseball," Brittain said.
Brittain added he expects big things from his team during the tournament, noting the team's overall 16-3 record.
"We're expecting to go all the way," he said. "I told the boys everything else is just icing on the cake."
Imperial coach Mario Gomez said the Reds are not discouraged by the defeat.
"We're going to try our best," Gomez said.
Reds manager Mark Buesch said the team will still make a mark in the tournament.
"We'll just give it another shot tomorrow," Buesch said. "We just picked a bad night to play our worst game of the season."
In other action, Calexico topped Seaview by forfeit after an injury to the pitcher in the fourth inning caused the game to be called. Seaview only had nine players and couldn't continue the game.
In the final game of the opening round, Holtville Little League Brave Travis Wilcox threw 15 strikeouts and hit a two-run homer in the fifth inning to lead his squad to a 4-3 win over the El Centro Little League Brewers.
"We had the offense at the right time and the defense at the right time," said Holtville coach Mark Allegranza. "(Wilcox's) home run fired up the team."
Allegranza said it's always a relief to advance on the winning side of a tournament.
"When you're a loser, you've always got that feeling that this is do or die," Allegranza said.
Braves manager Mike Wilcox said he was happy to see his team do well, adding he was worried it would come out flat after having nearly a month off between games.
"Coming out and getting the first one is very exciting," Mike Wilcox said. He added his team needs some work on defense if they plan on advancing in the tournament.
In the winners' bracket, Calexico will take on Brawley at 7:30 tonight on field No. 1 at Sunbeam while Holtville will play Sunbeam at 7:30 tonight on field No. 3. In the losers' bracket, Imperial will go up against Seaview at 5:30 tonight on field No. 3. El Centro will play at 7:30 p.m. Friday against the loser of the Calexico-Brawley contest.