Manchester United's assistant manager, Carlos Queiroz, insists that winning the Premiership alone will not satisfy Old Trafford this season and that the club are looking to emulate the achievement of 1999 and challenge for the treble.

Queiroz claims the Premiership has become a two-horse race with Sir Alex Ferguson's side six points clear of Chelsea after a fantastic first half of the season. But Ferguson's No2 warned yesterday that the players cannot afford to relax, and that in addition United are desperate to win the FA Cup and Champions League.

"It's not enough for us to compete only for the league. We also have ambitions and a great desire to win the other competitions as well," Queiroz told Manchester United Radio. "The reality at the moment dictates that the championship will probably be a two-horse race. But that isn't the case when it comes to the FA Cup and Champions League. It's wrong to think those competitions are also between us and Chelsea."

Aston Villa, beaten 2-1 in the FA Cup third round on Sunday with Ole Gunnar Solskjaer's last-minute goal, return to Old Trafford on Saturday and Queiroz warned that Chelsea are waiting to pounce on any slip-up.

"We deserve our position because we're playing the best football in the league at the moment and all the lads are doing very well," he added. "We haven't won anything yet though. We're in a good position as a result of our hard work, commitment and concentration and we must keep that going until the end of the season.

"The race will not be easy and I'm sure Chelsea will not give us any chances to make mistakes. We cannot just enjoy the fact that we're six points clear, we need to build on that. If we don't, then that is when you make mistakes and one small mistake could represent big punishment for us. Letting our focus and our state of alertness slip even just a little bit is the wrong attitude for us."

The Portuguese coach also believes there is still room for improvement among the United players. "There is no perfection within the game. There is always room for improvement both from an individual and a collective point of view.

"We have very much enjoyed the team's performances recently and cannot ask any more from the players regarding their attitude, concentration, discipline and the team spirit because it has been fantastic. But during the week there is no room for fun, there is only room to work. And we will continue to work on the specific areas we feel we can improve upon."

The Tottenham captain, Ledley King, is on the verge of making a return to training after missing the last three games with a bruised left foot. The 26-year-old, who struggled with a knee injury earlier in the season, was rested as a precaution following the Boxing Day win over Aston Villa, and Tottenham have not won since.

"I'll be back soon and it is improving quickly," he said yesterday. "It was building up gradually, just a feeling at the sole of my foot that wasn't right. It is something I have felt before and I knew what would happen next. I spoke to the physios, went for a scan and it was right that I rested when I did." PA