Center fielder Chris Young and second baseman Orlando Hudson were in the first two spots, and after thinking early in the spring that he would hit first baseman Conor Jackson third and left fielder Eric Byrnes fourth, Melvin flipped the pair.
"I think right now Conor is driving runs in," Melvin said. "So I'm confident with him at four."
Catcher Chris Snyder, who hit eighth last Opening Day, has worked his way all the way up to fifth by virtue of his strong second half in 2007 and a good showing this spring.
"The past couple of years, I've put a lot of effort into improving my offensive game," said Snyder, who hit .292 last year in the second half. "I had a good spring and I want to keep it going here in the regular season. It's going to be my same approach. Being in the heart of the order, there will be more situational opportunities -- more times when I have to get guys in. I'm still going to use the big part of the park, focus on going gap to gap."
Third baseman Mark Reynolds, who smacked 17 homers in 366 at-bats in 2007, will hit sixth and shortstop Stephen Drew seventh. That leaves 20-year-old right fielder Justin Upton in the No. 8 hole, which was not where Melvin had wanted him to hit.
The eighth spot in the order can be a tricky one for a young player to occupy because of the way opposing teams will at times pitch around someone hitting there.
"Our lineup could change, especially five through eight," Melvin said. "I didn't want to hit Justin Upton eight, but I don't really have anyone [else] to bat eighth."
Steve Gilbert is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.