Sept 9 (Reuters) - Manchester United forward Cristiano Ronaldo says his return to Old Trafford is not a vacation and he hopes to prove himself again with consistent performances over the next three to four years. The 36-year-old Portuguese spent six seasons at United between 2003-09, winning eight major trophies, and rejoined them from Juventus last month on a two-year contract. Having been handed the Premier League club"s famous number seven jersey once again, Ronaldo is hoping to reach the heights he did in his first spell at the club. "This is why I"m here," Ronaldo said in an interview posted on United"s website on Thursday. "I"m not here for a vacation... Before was good, winning important things and I wore the shirt before many years ago. "But I"m here to win again. I"m capable, me and my team mates. I"m ready to go. It"s a good chance for me, for the supporters, for the club, to get one step ahead. "I think I will be a huge thing in the next three or four years." Ronaldo, who has scored 118 goals for United, could make his second debut for the club when they take on Newcastle United in the Premier League at Old Trafford on Saturday.