The Brazilian, who locks horns with the league leaders on Monday night at Stamford Bridge, admits Roberto Mancini\'s men have quality but says his team can still challenge for title.Chelsea star Ramires has warned title-chasing Manchester City that they have won nothing yet.Roberto Mancini’s side are currently top of the Premier League, 10 points clear of Andre Villas-Boas’ men in fourth. City are now the favourites with the bookies to dethrone Manchester United as champions and win the title for the first time since 1968. But ahead of tonight’s big game at Stamford Bridge, Ramires insists the big-spending visitors should not count their chickens yet.Ramires said: “I just don’t think it is dead certain they will win the league.“It has been said before and their challenge has faded at the end.“As a matter of fact, we finished above them last season.“Manchester City have certainly had an incredible start.“They have invested a lot in players and managed to put together a formidable side. The quality of their squad in unquestionable.“But it is still very early to say they will win the title.“They beat Manchester United at Old Trafford by an impressive margin but they still need to be tested against the top sides, including us.“We are certainly looking forward to locking horns with them.” Chelsea have lost three of their last six league games but have won their last two to move back into the top four. And despite their inconsistent form, Ramires insists the 2010 champions can still challenge for the title.He said: “We know still we have potential to do well this season.“At Chelsea, we don’t train or play to answer the critics.“But at the same time it’s good when people write us off“It give us more peace to work and focus on what to do on the pitch.”  Ramires has scored three Premier League goals this season – four behind top-scorer Daniel Sturridge. And the Brazilian midfielder reckons Sturridge could be England’s secret weapon at next summer’s Euro 2012 finals. He said: “I really like Daniel’s style and he has been brilliant for us this season. He is so strong and skilful. “The form he has shown for Chelsea this season is also good news for the England team ahead of Euro 2012. “If he keeps improving, I don’t see how he could be left out of the England team.”