SoccerRoy Keane has reiterated his intention to end his playing career in 18 months' time - despite his recent impressive form for Manchester United. The 33-year-old is ready to disregard the evidence of the past four weeks and wreck the hopes of his manager by calling time on his playing days at the end of next season.

Seven days after Alex Ferguson claimed Keane's immense contribution to the Old Trafford cause would still be being talked about in 500 years' time, his captain revealed that his current contract, which expires in 2006, would be his last.

Over the past month alone, Keane has rampaged over Liverpool captain Steven Gerrard at Anfield and squared up to Patrick Vieira in the Highbury tunnel in a show of aggressive force that set the tone for United's 4-2 win. He then capped an exceptional display against Birmingham last week by netting his 50th goal for the Manchester side.

Such has been the magnitude of those performances, suggestions were being raised that Keane would be offered a new contract. However, the former Republic of Ireland captain has revealed he is not looking to extend his stay at Old Trafford, meaning he could end his career at the World Cup, four years after he infamously walked out on the last one.

"When I signed this contract, I believed it would be my last playing contract and I still believe that will be the case," he said.

After being forced to overcome a major hip operation and cruciate knee ligament surgery, Keane may count himself fortunate to be playing at all, let alone the standard he is currently reaching.

The former Cobh Ramblers and Nottingham Forest midfielder is unlikely to allow his impending retirement plans interfere with his preparation for tomorrow's Manchester derby at Eastlands as United look to maintain their title challenge.

Apart from long-term injury casualties such as Ruud van Nistelrooy and Alan Smith, who will return to training next week, Ferguson's only injury worry for the game is Cristiano Ronaldo.

Chelsea's Damien Duff was responsible for the tackle on Ronaldo during Wednesday's friendly international which has left the Portuguese winger battling to overcome a calf problem, although the United manager accepts the Irish winger is not a malicious player.

"It was a tackle from Duff that did the damage, which is a surprise because he is not that type of player. These things happen in games I suppose, but he (Ronaldo) is certainly doubtful."