Johnson's spring debut today

Randy Johnson plans to make his first start of the spring today against the NL champion Colorado Rockies in Tucson, Ariz. The 44-year-old left-hander is expected to pitch 2 innings, another sign of progress as he returns from back surgery.

Johnson went 4-3 with a 3.81 ERA in 10 starts for Arizona last season, the last on June 28, before undergoing his second back operation in less than a year.

Diamondbacks manager Bob Melvin said he hasn't projected Johnson's first regular-season start. The Big Unit enters the season with 284 career wins.

"It's all going to be outing to outing," Melvin said. "With him, we're not even close to that yet."