Lyon had been given a few days off from pitching in games recently to spend extra time in the bullpen working on his fastball command and ironing out a couple of mechanical issues.
Thursday, he looked better in allowing one unearned run in his lone inning of work.
"I felt good," he said. "I feel like my control and the life on my fastball are back. I had some mechanical problems, standing up more when I was releasing the ball instead of getting out in front and getting out in front of my front leg. So I took a couple of days on the side to see if I could repeat my delivery. I feel much better. I'm starting to feel like everything is coming together now."
That's what the D-backs want to hear after naming Lyon their closer following the offseason trade of Jose Valverde and his Majors-best 47 saves to Houston.
Lyon will pitch in Friday's game against the Rockies and then be off Saturday and Sunday before Monday's opener in Cincinnati.
"His sinker just wasn't moving the way he wanted it to move," D-backs manager Bob Melvin said of Lyon's earlier struggles. "It wasn't doing what he wanted it to do there. I think he's made some progress in his last two bullpens. He'll be mentally ready to go on Opening Day."
Steve Gilbert is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.