After only two matches of the new season the biggest threat to Chelsea's ambition to retain their title may come from disgruntled players in the dressing room rather than the opposition on the pitch.

Jose Mourinho's highly-paid, multi-talented champions have not been at their best and have still gained 1-0 wins over Wigan and, more significantly, title challengers Arsenal [Images].

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After the last gasp victory at Wigan, Mourinho tore into his players before joking: "To play so badly and to get three points we must be very, very good."

On Sunday a lucky goal off Didier Drogba's [Images] knee broke a 10-year winless streak against last season's runners-up Arsenal, handing the west London [Images] side a big psychological boost.

"The first game we played badly, the second game we played ok," Mourinho said. "We know we can improve."

Backed by Roman Abramovich's billions, Chelsea were able to bring some 70 million pounds of substitutes off the bench against Arsenal. Seven international players did not even make the squad.

Among them was Portugal defender Ricardo Carvalho, who suffered a dressing-down from his boss last week after voicing his displeasure at not being picked for the opening match.

Mourinho fined Carvalho and let rip at him in front of his team mates, before questioning the player's IQ to reporters.

RUBBING SALT

Nor did he let the matter lie after an apology from the defender, rubbing salt into his compatriot's wounds in the match programme on Sunday.

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"One of the many reasons why Chelsea were champions last season was because everybody thought about Chelsea and nobody had selfish feelings," he wrote.

"Maybe when you are reading this, maybe Riccy is sitting in the stand not on the bench or on the pitch, maybe he is also reading this and maybe he understands now."

Carvalho was not alone in voicing disquiet, however.

Winger Arjen Robben, who took Stamford Bridge by storm with his dribbling skills last season, also went public with worries about the depth of the squad, saying he did not want to be left on the bench in a rotation system.

Mourinho was more forgiving of the Dutchman, who played the first hour against Arsenal although he will not be starting the next game against West Bromwich Albion.

"It is completely different...He has an opinion, he expresses that opinion. I know about it before I read it in the press," Mourinho said.

"But of course I don't change my mind ... next Wednesday he will on the bench."

Robben's absence could mean a first start for Joe Cole, who made the England [Images] side last week but was not even in Chelsea's squad against Arsenal.

Questioned about Cole, Mourinho lamented the FA's policy of sticking to five substiutes instead of the European norm of seven.

"If today we were in Spain, Italy [Images], Germany [Images] or Portugal I would have Joe on the bench," Mourinho said on Sunday.

Scant comfort for a man aiming for a permanent spot in England's midfield in a World Cup season.

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