London - Jose Mourinho believes his Chelsea side have improved sufficiently in 2014 to justify their position as Premier League leaders.
A 2-0 victory over West Ham at Stamford Bridge on Boxing Day, courtesy of goals from John Terry and Diego Costa, kept Chelsea three points ahead of last season's champions Manchester City.
The Blues, who finished third last season, will have their title credentials tested again against Southampton on December 28, but Mourinho is confident his players can rise to the occasion at St Mary's and finish the calendar year on top.
"We are a much better team when we have the ball," he said. "Last year we were very strong defensively but lacked a bit of creativity when we had the ball. The challenge was to bring that dynamic without losing the qualities of the team.
"At the beginning of the season there was a little bit of conflict between those two ideas and we made defensive mistakes. At the moment we have a good balance.
"The team is happy to have the ball and also comfortable when the opposition has it. We are a very good team."
Sunday's trip to the south coast will see Mourinho renew his relationship with Southampton manager Ronald Koeman.
The pair were colleagues at Barcelona when Manchester United manager Louis van Gaal was in charge at the Nou Camp.
"I was there before him," Mourinho added. "Obviously he was a very big player for Barcelona but he left.
"I arrived there in 1996 and I think Ron came back in 1999 so I was already a member of the technical staff.
"We helped each other but we were there to help Mr van Gaal because he was the boss then. I think we did our work quite well.
"I know that he is a good coach and I know the football principles that he defends and he likes.
"When I saw him get his hands on (Mauricio) Pochettino's team I thought he was the right guy to do it.
"Obviously they lost some good players but they were very clinical in their choices.
"They don't have any pressure because they are very, very far away from relegation and the title is not for them. They are in a fantastic situation to play beautiful football."
Mourinho reported no new injury worries for the Southampton game and revealed he had made alterations to the training schedule to make sure his squad remained in peak condition over the hectic Christmas period.
"I had two training sessions for Saturday but they were crying so much in the dressing room I decided to make a change," he added.
"They are training now so tomorrow, instead of two sessions, there is only one. They are human, like the Southampton guys are human. It will be very difficult for us and for them."
It took a long time for West Ham to threaten Chelsea, although they did hit a post late on through substitute Morgan Amalfitano.
Hammers manager Sam Allardyce was disappointed with his players' first-half showing and will be sure to demand a reaction on Sunday when they host Arsenal.
"We didn't play like I asked the players to play," Allardyce complained.
"They got too sucked into a negative style, passing it sideways and backwards, instead of forwards into the right areas.
"As good as Chelsea were and our goalkeeper was in great form, but the two goals were so avoidable.
"I have no complaints about the result. Chelsea are a top quality side and we found it difficult to compete with them.
"I'm angry with the first half, the way we approached the game. I expected us not to play that way.
"I had to set out the tactics against a side of the quality of Chelsea. When it doesn't happen, you get frustrated."