Rivera spoke with ESPN Radio's Michael Kay on Monday, and stressed that while he's unsure about returning this season, he isn't ready to rule out the possibility.
"That's my goal," Rivera said of pitching again this year. "Definitely, that's my goal. I'm not thinking about it because if it doesn't happen, I will be disappointed. So I'm taking it day by day. I'm working hard and doing what I'm supposed to do. I don't want to put something in my mind.
"I want to make sure that I do my things first. That's what I'm doing, that's the way I'm thinking. Day by day, positive, optimism. Whatever the Lord will allow to happen, that will happen."
Rivera tore his right ACL on May 3 while shagging flyballs in the outfield before a game in Kansas City. He underwent surgery on June 12 after dealing with a blood clot in his leg following the injury, and he's reportedly healing quickly.
Returning this season once seemed out of the question, but with the progress the 42-year-old has made, it might be time to start thinking about whether or not it could happen — even if Rivera himself doesn't really have much of an idea just yet.
"I don't know," Rivera said of a return. "I don't know. I can't answer that. I want to. I want to be there now. Only God knows."
Rivera, who is the MLB's all-time saves leader, was 1-1 with a 2.16 ERA and five saves in nine games this season before going down.