Roberto Mancini hopes Manchester City's 4-0 win over Leeds United that secured their place in the FA Cup sixth round is the "brodino", or soup-starter, to a comeback in their title defence. Mancini is hopeful that his captain, Vincent Kompany, will be fit for the first time in a month following a calf injury to lead this challenge.

Goals from Yaya Touré and Carlos Tevez plus a Sergio Agüero double gave City a first win in four matches, though by the time Chelsea are welcomed on Sunday they could be 15 points off the pace as Manchester United play the day before.

Asked if the win could help kick-start City's challenge, Mancini said: "In Italy we say a game like this is a brodino – a starter. I hope it can happen that we start to win in the Premier League again."

The Italian is unfazed that his side might be 15 points behind United when Chelsea visit. "This is possible, but I think we should always be confident in ourselves, even when we're 12 points behind at this moment," he said. "We lost seven points in [our last] three games and this can happen for any team. But now they [United] play a lot of games, at this moment they deserve to stay there because they have been better than us and scored more goals than us."

Mancini is hopeful that the FA Cup can again be won following their 2011 triumph. Of the victory over Leeds, he said: "I'm happy because it was important to win after Southampton – the FA Cup is difficult. We started this game very well, we started very quickly and scored two goals, after [that] it was easier. Arsenal showed this yesterday [in being knocked out]. Every game in the FA Cup is difficult if you don't have a good approach.

"Every team plays like it's a Champions League final. The FA Cup is an important trophy in England because you should play 100% if you want to win."

Agüero's double took him to 13 goals for the season, Tevez's strike made it 10 for him, and with City having scored 14 fewer than United in the league, Mancini hopes their form can be consistent. "Our strikers need to continue to score like they did today," he said. "If they do that, we can have other chances. I hope Sergio will be like this from now to the end of the season because if he is and our other strikers continue to score until the end, then I think the championship isn't finished."

Kompany and Gareth Barry, who was unavailable because of a foot problem, should return to face Chelsea. "Gareth was nothing, I think he will be ready," Mancini said. "We hope we can recover Vinny for the next game." He said of Javi García, who was replaced in the second half: "We will see tomorrow or Tuesday, I don't think it's big problem."

Neil Warnock, the Leeds manager, suggested his future may be in doubt under the club's Dubai-based owner, GFH Capital. This week is the one year-anniversary of his appointment but Warnock admitted it is the owner's right to remove him. "It's their prerogative. I have spoken to them at great length. If they think it will help them then I'm not against it," he said.

"I think whatever is best for Leeds United really. If I'm a bit too long in the tooth [then so be it]. I came at a difficult time, but given what has gone on behind the scenes over the past 12 months I think I deserve a medal, if I'm honest."

Does Warnock think he could be sacked? "You could ask that of anybody – you can't be sure of anybody when you look at some of the situations this season," he said. "My contract ends in the summer and there's no way I want to stay in the Championship next year.

"I've known that all along – my one intention was to go up. That's why I'm living away from the family. She [his wife Sharon] let me have one go to try to get an eighth or ninth promotion."