While striker Diego Costa's 10 goals in 11 league matches, having added to his total with the winner in Saturday's 2-1 victory at Liverpool, and Cesc Fabregas' creativity in midfield have given Jose Mourinho's side undoubted quality there has been a shift up in terms of character.
Mourinho pointed to as much when he praised his team for the ambition they showed at Anfield, especially in the second half having come back from an early Emre Can goal to equalise through Gary Cahill.
The Portuguese claimed most sides would have been happy to take a draw at Anfield but his team were not as Azpilicueta, back in the starting line-up after suspension, agreed.
"I think we are stronger mentally now
The players who came have given us another dimension as well," he said.
"I think you saw that
When the team was losing we were still really strong mentally.
"The whole squad know we have to fight together
Some players have more talent, some score goals, and sometimes we have to defend for them - but the main thing is we do it all as a team.
"We got it back to 1-1 pretty soon and after that did very well
Obviously we'd prefer not to go behind but that is going to happen at times.
"Over the last few games maybe we haven't played our best football and the scores have been tight but over the whole season you know that everyone can't keep playing very well and winning easy.
"We knew it would be tough here (at Anfield) but we fought so hard until the end - the aim was just to get those three points and we did.
"Last year we were so close to winning the title and this year we know it will be tough but that's what we want.
"We will see in May
We're on top of the table but that's a long way off, but we want as few problems as possible up to then."
The impact of Costa, who Mourinho believes is now over his injury problems, cannot be underestimated so far this season and he gives his team-mates the confidence they will always score.
"We're lucky to have three really good strikers
We showed it when he was out, when Didier (Drogba) and Loic (Remy) came in and were scoring," added the Spain international.
"Now he's back and scoring
He plays with high passion, he's always fighting for team, and is even after goals in training - he's a great finisher.
"If we analyse him he scores but helps so much in the team
Even in last five or 10 minutes he was pressing high and doing his job
That's great for the whole team."
Source : PA