Chelsea have paid PSV Eindhoven 12 million pounds (22.3 million dollars) for Robben who joins the English Premiership side in the summer.

"I must admit it was a bit of a kick in the teeth after two months out to hear about it," Duff told The Sun. "But I will just have to carry on doing what I always do and work hard."

Duff's progress at Chelsea since his 17 million pound (27 million dollar) move from Blackburn last year has been hampered by shoulder and Achilles tendon injuries.

The Republic of Ireland star is poised to make a return to first-team action after playing for Chelsea reserves in midweek.

"I hear that Robben is a left-winger but I do not play there very often so maybe I will get a game somewhere else in the team," said Duff.

Cole was also dismayed at the decision to sign Robben but he has insisted he is ready to fight for a first-team place.

Cole said on his personal website: "I am disappointed that I have not been playing regularly this season. Like any footballer I want to be playing every game.

"I have been to see the manager on a number of occasions this season but that is the same as all the other players.

"Claudio Ranieri has assured me that I still have a big future at Chelsea and I am part of his long-term plans.

"I have certainly not asked for a transfer and am determined to win a regular place in the Chelsea first team.

"I want to assure Chelsea fans that I will not be seeking talks with the manager in the near future and am solely focusing on our next game against Stuttgart in the Champions League next week."

Cole, 22, has not played a full 90 minutes for Chelsea since his 6.6 million pound (12.3 million dollar) move from West Ham.

He has started just 11 Premiership games and been substituted in every one of them.

He was also offered to Charlton when Chelsea signed Scott Parker -- a rival for his midfield spot -- but Charlton preferred 10 million pounds (18.6 million dollars) in cash.