Manchester City midfielder Gareth Barry cannot put his finger on why Roberto Mancini's side have stumbled but he is targeting eight wins from eight in the title run-in.
Manchester United were off the pace until recently and are now level with City at the top of the Barclays Premier League. The derby rivals must still meet in a derby at the Etihad Stadium on April 30.
City drew 1-1 at Stoke on Saturday when Yaya Toure scored a late equaliser following Peter Crouch's stunning opening goal.
And with United facing Fulham tonight in a game which could see them go three points clear, City's recent downturn in form has left Barry scratching his head over what has happened to the early pacesetters.
The England international said: "It is really hard to pick anything out.
"It was always going to be tough to keep the blistering start we had going, the run we had was fantastic.
"People were saying we were unstoppable but it is such a long season, it is tough to keep that going.
"We have got eight games now, we must try to win them all."
Stoke striker Crouch is keen to improve his international prospects ahead of Euro 2012, as he targets an England place.
Crouch said: "I knew right from the start when I signed for Stoke that, if I was playing well and scoring goals, I would have a chance of being involved in the England set-up.
"I know if I am working hard and playing well I will get a chance and hopefully I will grab it with both hands."
Arsenal tightened their grip on third place as goals from Kieran Gibbs, Theo Walcott and Mikel Arteta earned the Gunners a seventh straight league victory over Aston Villa at the Emirates Stadium.
The win left manager Arsene Wenger praising the strength of his defensive unit.
He said: "When we did not win games [earlier in the season], I did not feel we played as badly as people said. We have gained a lot of confidence in our play out from the back and that makes a massive difference."
Tottenham maintained their five-point lead over Chelsea in the race for the fourth Champions League place after a goalless draw at Stamford Bridge.
Spurs attacker Rafael van der Vaart is hungry for a Barclays Premier League and FA Cup double after helping Tottenham take a huge step towards a top-four finish.
He said: "We want to end in the top four and win the FA Cup - it would be great."
Spurs must first beat Bolton in tomorrow's re-arranged cup quarter-final tie with Bolton which was abandoned following Fabrice Muamba's cardiac arrest at White Hart Lane.
The reward for the winners will be a cup semi-final against Chelsea.
Van der Vaart added: "It would be a dream, especially at Wembley. For me, it's going to be the first time. So, let's win Tuesday and then get Chelsea."
Also on Saturday, Bolton ended an emotional week on a high as they secured a 2-1 win over fellow strugglers Blackburn which lifted them out of the bottom three.
Two headers from David Wheater put Bolton ahead before Steven Nzonzi pulled one back for Rovers.
Wolves' woes continued as they let a 1-0 lead slip to lose 2-1 at Norwich, their fourth defeat in a row, while Shaun Maloney and Gary Caldwell scored for Wigan in the 2-1 win at Liverpool.
Nicklas Bendtner, James McClean and Stephane Sessegnon scored as Sunderland won 3-1 at home to QPR whose late consolation came from Taye Taiwo.
QPR, who replaced Bolton in the relegation zone, also had Djibril Cisse sent off.
Leighton Baines and Nikica Jelavic scored as Everton won 2-0 at Swansea.