"I just went through my regular warmups, played catch and then got ready like I was going into a game and then they [hitters] stepped in," he said. "Today was 100 percent go. I threw all my pitches like I would in a game and felt really good."
The difference was that the hitters stood in the batter's box, but didn't take any swings.
"It's just now getting the hitters in there and start swinging," Collins said. "I'm ready to get going."
He's been on the disabled list for the full 15 days, but is not yet ready to come off.
"It was a flexor muscle strain," he said. "For me, it was just not being able to warm up as quick as I used to be able to; it took a lot longer to warm up. Then when I'd go into the game, it'd tighten up a little bit. It wouldn't stay warm."
He's expected to go on a Minor League rehabilitation assignment before returning to bullpen duty.
Left-hander Francisley Bueno, also on the DL, didn't throw as expected Tuesday because his bruised left pinky has been slow healing.
Collins and Bueno each pitched just twice for a total of one inning before being disabled.
Dick Kaegel is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.