London - Jose Mourinho has said Chelsea's win away to Crystal Palace on Saturday showed they have the character to maintain their Premier League title challenge.
WRAP: English Premiership
The Chelsea manager was heavily critical of his team when they lost at Selhurst Park last season and when asked what his players lacked in the game, wrote the word "balls" in a reporter's notebook.
Seven months on, Mourinho was asked what had been the key to his side's 2-1 victory and this time wrote "big balls" in the same reporter's notebook.
Victory -- secured through goals from Oscar and Cesc Fabregas and achieved after both sides had been reduced to ten men following the dismissals of Cesar Azpilicueta and Damien Delaney -- maintained both leaders Chelsea's unbeaten start to the league campaign and their five-point advantage over reigning champions Manchester City.
This latest victory was achieved without the injured Diego Costa, Chelsea's leading scorer this term with nine goals in his first seven league game.
For Mourinho that was a sign his squad had improved as a whole rather than just been strengthened by the arrival of Costa and fellow pre-season signing Fabregas.
owever, the Portuguese boss said it was too soon to talk of the Premier League trophy returning to Stamford Bridge.
"If we were in another league, another profile of league, I would say immediately 'yes, we will do it'," Mourinho said.
"In the Premier League, we can do it. But it's hard to say we will do it.
"There is a long way to go, lots of good teams and difficulties, difficult games and runs in front of us."
He added: "The only thing I will say is what is obvious: we are a better team than last season, there was a clear evolution in our team, and not just because we brought in two fantastic players.
"One of them wasn't playing today, but our team was still fantastic. I'm pleased. But to win the title, it's a long way away."
Mourinho confirmed Costa would miss Tuesday's Champions League clash with Maribor after the striker returned injured from international duty with Spain.
"No, he can't play on Tuesday. I have no idea (when he can play).
"The only thing I can say is that, after Arsenal, he went to the national team. He played two big matches against Slovakia and Luxembourg, and he came (back) in a condition where he's not available to play for his club."
Mourinho then made it clear what he thought of the Spain set-up by adding, sarcastically: "I think he (Costa) will be in great conditions in mid-November to be back for the national team. That is for sure.
"Our medical department will take good care of him and he will be in perfect condition. He will play for me when he has free-time from the national team."
Oscar put Chelsea ahead with a sixth-minute free-kick but the balance of the game changed after the two dismissals.
Blues left-back Azpilicueta was sent off for a 39th-minute challenge on Mile Jedinak and was quickly followed by Delaney who collected a second yellow card three minutes later.
Fabregas doubled Chelsea's lead in the 51st minute and Fraizer Campbell's 90th minute reply came too late to affect the outcome.
Palace manager Neil Warnock acknowledged Delaney's dismissal had proved decisive -- the defender twice fouled Loic Remy -- but was critical of the performance of referee Craig Pawson.
"It was a silly thing to do, to give the referee a decision to make," Warnock said. "I thought Chelsea influenced him at times today, but he's young. Inexperience, I guess.
"He's had better days. But we played really well, should have scored two or three in the first 45 minutes. I really enjoyed it.
"It's just disappointing that, on another day, we might have got a result if things had gone our way."