Signed as a free agent in the offseason, Hoffman gave up a leadoff double to Jack Hannahan. Baseball's career saves leader retired the next three batters.
A crowd of only 2,564 attended the spring training opener for both teams. The game was called because the visiting A's were out of pitchers. Both teams used eight pitchers.
Corey Hart homered, singled and stole a base for the Brewers.
Hart became the first player in Brewers' history to record a pair of 20-homer, 20-steal seasons when he did it in 2007 and 2008. But he slumped last September, batting .173 with no homers during the Brewers' drive to the NL wild card.
"I was excited to get back out there. I had some good at-bats that felt good," Hart said.
Hart singled down the left-field line after being jammed by a breaking ball in the second inning and stole second. He hit an opposite-field homer to right in the fourth.
New Brewers manager Ken Macha said he'd been told Hart chased a lot of sliders last year.
"He comes up today, hits a home run to right. That's staying on the ball, staying down in there and having the ball travel a little more. That's encouraging," Macha said.
Milwaukee RHP Todd Coffey, who pitched a scoreless fourth inning, is scheduled to fly to his home in North Carolina on Thursday to be with his wife for the birth of their third child and first son. Coffey has set a bullpen session in a high school gym in North Carolina on Saturday before returning for his next exhibition game appearance Monday or Tuesday. ... Reliever Eric Gagne threw 27 pitches in a bullpen session Tuesday but will need to throw batting practice at least once before he is ready to make his spring debut, Macha said. ... 3B Bill Hall, recovering from a slight tear in his left calf, is expected to run the bases for the first time Thursday, Macha said. Hall has taken ground balls and hit in batting practice. "His progress has been terrific," Macha said.