The right-hander, who is bidding for a spot in the rotation after spending the past five seasons as a reliever, allowed two runs on six hits. He did not walk a batter and struck out three.
Both of the runs came on a fourth-inning homer to left by Dodgers slugger Matt Kemp.
"I was able to make some adjustments from my last start and kept the ball down for the most part," Heilman said. "I hung a ball to Kemp, and he doesn't miss many of those. Arm felt good, body felt good. I feel like I'm right where I need to be."
2010 Spring Training - null
Sights & Sounds
Spring Training Info
D-backs manager Kirk Gibson has been impressed with the way Heilman has approached the competition. Heilman spent the winter working on his conditioning and stamina so that he would be able to pitch deep into games.
"I felt like I was settling in [after five innings]," Heilman said. "It felt like I could have kept going out there. I didn't feel tired, so I felt like the work I put in during the offseason has really helped and put me in a position to compete."
Heilman is battling with Armando Galarraga and Barry Enright for the final two spots in the starting rotation.
As a reliever, Heilman threw his fastball and changeup almost exclusively, but as a starter he'll need a third pitch for when he faces hitters multiple times in a game.
To that end, Heilman has worked a lot on his slider this spring, and he threw a bunch Thursday.
"Just one of those things you have to mix in," he said of the slider. "It's certainly not going to be my bread and butter, but it's another pitch to keep hitters guessing, keep them off-balance and keep them honest. That's the name of the game. You want to get them out with your best pitches, but be able to throw the slider for a strike, be able to bounce it when I need to and mainly just not get hurt with it and continue to pitch on fastball-changeup, which is what I've had my most success with."