"It is great for Paul to be in the final," said Ferguson.
"It was a fantastic goal.
"I don't think you can expect him to score 10 or 15 goals a season like he used to. But when he gets one like that it makes up for the ones he can't score.
"It is a marvellous moment for him.
"He's one of the great players to come through the ranks here.
"We needed a fantastic performance and we got one," the United manager added.
"I knew it was going to be a long night but I felt we could have scored three or four in the first half.
"It was a bit nervy in the second because they had to have a go at 1-0 down.
"But we got through that spell and, in the last 15 minutes, I didn't think they made any chances.
"It was emotional at the end but you expect that at a semi-final. The important thing is that we are there and we deserve to be there."