The 40-year-old Contreras, who began last season as the Phillies' closer and was 5-for-5 in save opportunities before he injured his arm and had to undergo elbow surgery, lasted just one-third of an inning and was ripped for four runs on four hits, leaving him with an ERA of 108.00.
But that didn't dampen Contreras' optimism about the season ahead.
"The one thing I'm concentrating on is location," he said. "I feel good. No pain. That's the most important thing. The slider was a little bit flat, high. The fastball was high, too. But I feel good. I feel strong.
"A couple more days, I'll pitch again. It's not a problem. I'm thinking two more days."
"He's just got to get some work in," said manager Charlie Manuel. "Today was a big step for him."
Contreras had pitched in two Minor League games this spring and declared after his second outing that he would be ready for Opening Day. He said he felt even better on Sunday.
"A lot better, much more strong," the pitcher said.
Sunday's performance aside, the presence of Contreras in the bullpen would make a huge difference, according to starter Cole Hamels.
"He's a great pitcher. We definitely missed him last year," Hamels said. "He's a big-time guy who knows how to get the job done. He definitely has some nasty stuff."