Chelsea captain John Terry has warned leaders Manchester United that the Blues have not yet reached their full potential this season.
Terry's team overcame a dogged Newcastle side thanks to a second-half matchwinner from substitute Didier Drogba to cut United's lead at the top of the Premiership to five points.
The Ivorian striker slid home his 15th goal of the season in the 74th minute to end Newcastle's stubborn resistance.
Now Terry insists that Chelsea are still capable of going up to another level as they begin the chase to catch Sir Alex Ferguson's men.
The England skipper said: 'Manchester United are probably playing the best football they can play at the moment. They've had very few injuries so far.
'Whereas we know as a team we've got another level to go to. We need to take the game to teams and then no-one can live with us. We must go on a run of games and keep winning.
'We must keep the pressure up. Christmas is a difficult period. United have got tough games. We must just keep winning and keep on like we know we're capable of.'
Chelsea struggled to break down Glenn Roeder's makeshift side until Drogba, a half-time replacement for the injured Ricardo Carvalho, slid the ball home after Andriy Shevchenko had miscued his shot.
Drogba, nursing a hamstring injury, was left on the bench along with Shevchenko at the start.
But unlike Drogba, the Ukrainian striker had been dropped by Mourinho who felt he wanted different qualities against United and selected Salomon Kalou, Arjen Robben and Shaun Wright-Phillips ahead of him.
Mourinho added: 'I make decisions from my analysis. I took him out of the team because I felt the team needed different qualities.
'With Salomon Kalou and Arjen Robben, I get different qualities. So we decided to make some changes and Shevchenko was out.
'I think (Shevchenko) took it as a professional. He was not happy but behaved properly. He came on when I decided and did well for the team.'
Mourinho left Drogba in the dugout until half-time because of his injury problem.
He added: 'Drogba was injured. A normal player, with a normal attitude would not have played.
'So I was trying to explain to him the best decision was to save him. If the result was positive at half-time we would not have played him.
'But I felt we needed him at half-time. His attitude in the game and the way he worked for the team meant he was very important for us. He is one of the top players at the moment.'
Roeder, already without 12 first team players, now looks set to lose Charles N'Zogbia for a lengthy period if scans on his knee show up severe ligament damage.
N'Zogbia was stretchered off after a collision with Frank Lampard, leaving Roeder lamenting his worsening situation.
'We had 12 injuries, that's not an excuse, it's a fact. Now N'Zogbia has ligament damage. We don't know how long he will be out or how bad it is at the moment. We will know more today.'