Keane was in the crowd at the AMEX and was mightily impressed by the 19-year-old, who McCarthy called-up to the latest Republic of Ireland squad.
McCarthy said today: "I didn't see it at the time but I've seen it since. Robbie was watching it.
"It was excellent. His goals were both very good. People talk about his second one. I thought his first one was brilliant, because his movement was good.
"He got across the defender and then, having had it saved, he had the presence of mind, he didn't just have a little dig at it and run off, he spun and put it in the net.
"I saw him against Armenia (under-21s) and I was really impressed. He really has some personality on the pitch, he plays with real personality."