The forward scored twice against Bayer Leverkusen in the Champions League, but his boss is unsure of the player's state of mind.
The England striker scored twice and grabbed an assist as the Red Devils swept past Bayer Leverkusen 4-2 on Tuesday, enthusing after the game that he was delighted to have scored 200 goals for the club.
But when questioned on the 28-year-old's current state of mind, Moyes said he does not know how his forward feels — only that he has looked sharp in training and during matches.
"I don't know," the United boss told ITV Sport. "I just know that he's been great in training, he's worked really hard, he's fit, he looks fit and lean, and he showed in his performance [Tuesday] again. I've only seen a few goals, I'm only just here. I said a month ago he's got a chance to join the real greats here with his goalscoring record.
"I thought his goals [against Leverkusen] were great. He got round the goalkeeper and that could've been the hat trick, obviously his second at the time, but he deserved the ovation that he got. His performance was terrific."
The new manager also reserved praise for the partnership that Rooney is developing with fellow striker Robin van Persie, who also scored against the German outfit.
"I think they're both such good players — Robin's goal as well was great," Moyes added. "Robin could have had another one as well. I said a week or so ago if we could get those two scoring the goals and the ratio through the season then they'd be formidable and obviously it would help get us as many points as we can.
"It was a good night. We did a lot of good things, missed a couple of chances which kept it a little bit anxious at one or two moments, but good job."