The Portugal international made just his fifth appearance since the turn of the new year, but he put in a great performance to fire his side to the quarterfinals of the FA Cup.
The Portugal international came on as a substitute and proved to be a catalyst for the Red Devils, notching in the second half with a close-range volley, before setting up Chicharito for their second goal of the match, which proved to be the game-winning strike.
Nani has only managed 16 appearances for the Red Devils this season and was linked with a January move to Serie A side Roma after finding his first-team chances at Old Trafford limited.
"I think everyone is always ready to help the team. I always think like that. If I get my opportunity I just want to get on and try to help the team," Nani told ESPN. "That's what happened, and I am very happy for this night.
The 26-year-old was involved in a car crash on Friday evening when a vehicle driven by a police officer hit his Bentley while responding to an emergency call; however, the attacker confirmed he was fine and was happy to be playing again.
"It was not a big crash, but yes I am happy to have nothing bad, but that's happened in life, the most important thing is today. I'm so happy for the beautiful day, and keep working hard," Nani said.
Chicharito hailed Nani's performance at Old Trafford and was relieved to get past a stubborn Royals side.
"We know that it would be very difficult thankfully we scored twice, so we are very happy," Chicharito said.
"We were struggling in the last few minutes, because Reading really went for it, but we were able to hang on. We knew that the rival in front [of us] was a very difficult one, and thankfully we scored twice in the last minutes.
"I think his [Nani] first touch he almost scored an unbelievable volley, so he was brilliant today. He scored, he made a few chances for us and the assist to me."