Otelul Galati barely warranted a mention from Manchester United's players as they filed out of the National Arena in Bucharest on Tuesday evening, although not because their performance was one to forget. All minds switched to Sunday after the defeat of Romania's champions, and a date with Manchester City that Nani admits will be the city's most important derby of the Premier League era.

Roberto Mancini's team will arrive at Old Trafford in the unusual position of looking down on United and seeking to establish a five-point lead over their rivals at the top of the league. There is no trepidation among Sir Alex Ferguson's champions. United have not dropped a point at home in more than a year, a record stretching back to the draw against West Bromwich Albion on 16 October 2010 and consisting of a remarkable 19 consecutiveleague wins. For Nani, that home form outweighs any improvement made by the league leaders this season.

"Every year the games against City seem to get more important," said the Portuguese. "They are playing well, they have a good team, they have good players, they are doing fantastic and of course it will be more difficult than other games. But we should not forget, we are United. We are playing at home and that is a big factor for us. We have a fantastic home record. Whenever we play the big games we have a positive attitude and want to win."

Last season's FA Cup semi-final between the two attracted the same billing as the rivals' first Premier League meeting but Nani insists City's victory then has no psychological bearing. He said: "All the players have forgotten that game now, especially as we beat City in the Community Shield at Wembley at the start of the season. It's important that we remember that rather than the semi-final or any other games we lose."

The United winger also dismisses the assumption that Sunday represents a gathering of the only title contenders the Premier League has to offer. "It is too early to say who is going to win the league or be second. There are a lot of teams who are doing well. Chelsea are doing fantastic. It is too early to say it is just going to be about Manchester United and Manchester City for the title."

Nani was among the selectfew in the United team who responded to the urgent need for a first Champions League win of the season in Bucharest. His recent record of three goals in three appearances against City will, he hope, also work in his favour.

"We usually play well against City. All the players want to play in these games, especially me. My confidence for these games is high and I feel comfortable in these sort of games. I like the pressure these games bring. I have been working hard and waiting for these games because I believe I have the quality and mentality to play in them. I scored a good goal against them last season but [Wayne] Rooney's was even better. I feel confident and comfortable I can score again."

Several hundred Bulgarians travelled to the Romanian capital on Tuesday in an attempt to persuade Dimitar Berbatov to reverse his decision to retire from international football. Their trip was in vain, however, as United's record but rarely employed signing did not take to the pitch to hear their acclaim and afterwards insisted he could not play for his country when he does not feature for his club. He said: "I would like to thank the fans, it was very pleasant. My team-mates wondered what was happening and I had to explain to them [about the noise from the stands]. I didn't expect such reaction. [But] I can't play for the national team if I'm not playing for my club. I want to get more chances because I know I can help the team. I'll continue to give my best to earn my place."

United, meanwhile, have granted the Football Association permission to speak to Patrice Evra as part of its inquiry into his claims that he was racially abused by Luis Suárez at Anfield on Saturday. Both players are expected to be interviewed, with Evra to give his submission this week.