The 36-year-old is set to make his second debut for United against Newcastle on Saturday, having retuned to Old Trafford from Juventus on a two-year deal.
And Ronaldo insists he hasn’t returned to the club for a “vacation”.
He told MUTV: “This is why I am here. I am not here for a vacation. As I told you, before was good, winning important things and I wore the shirt before many years ago, but I am here to win again.
“I am capable, me and my team-mates. I am ready to go, I am ready to go. It is a good chance for me, for the supporters, for the club, to get one step ahead.
“I am ready and I think I will be a huge thing in the next three or four years.”
The Portuguese superstar scored 118 goals in 292 appearances during his first spell with the Red Devils.
He won three Premier League titles, the Champions League and his first Ballon d’Or award in his five-year spell.