Guus Hiddink has refused to get involved in the debate concerning the recent struggles of compatriot Louis van Gaal at Manchester United because he has "enough problems" at Chelsea.

Van Gaal remains under immense pressure at Old Trafford with United currently in fifth position in the Premier League.

Hiddink has helped Chelsea show glimpses of improvement since taking charge as interim manager in December but his side are still languishing in 13th, 16 points from the Champions League places.

"This is a big match," he said ahead of Sunday's meeting with Manchester United at Stamford Bridge. "Both have been big clubs, through the years. You know the recent history of this club. Of course they have under-performance.

"We are getting a bit back on track though I would like to have more victories than unbeaten draws but step by step the team is more stable and we hope to go into a beautiful spring time.

"It's difficult for me to judge their problems, I have enough, not sorrows here because I like the job and the players and staff are working with a lot of ambition, but I am not going into the problems from other clubs as well.

"I have a professional relationship with Louis. We haven't met that much in our professional life in Holland. A few times but not many.

"We can talk the whole morning about Manchester United but I am wearing a different colour. Every club during the season has periods where they might worry a bit. We had that as well so I don't like to go too much into other people's kitchen.

"Louis has to perform, that is normal as we have to perform here. There is pressure and still is a big ambition and they have to cope for that. The pressure is on, it's on everyone but if you have the possibility to go into the first position then the pressure is on."

Chelsea have a near full-strength squad although Alexandre Pato, on loan from Corinthians, is still not close to consideration.

"The squad is looking OK after Watford," said Hiddink. The players have come back in and they seem to be very fit except that (Radamel) Falcao and (Loic) Remy are not. For the rest it seems to be very good. Pedro did good training this morning and we will see how he reacts after an upper leg injury but I don't think there will be big problems.

"Pato is in his pre-season and we have made a training plan which he is doing now every day at least once but lots of days twice training which means he is getting his fitness but not full fitness yet he needs to be fine tuned. We made a good plan.

"He will not be in for the upcoming few games. We want to have him fit not going too early for the risk of injury in this tough league.

"He is skilful that's what we know. He is ambitious of course but he needs more physical fitness. He played his last game on 28th November.

"I hope he can have an impact but that's why it is good to have him on loan and not already in a next situation where the club has offered him a longer term so it's good for both parties and they can see whether they fit."

Hiddink insists there has been no development on any further talks with John Terry as the captain gets ready for a first home game since he announced he will be leaving in the summer.

"I don't notice any change because first of all he is a very experienced player. He has gone through good things and storms in football which means he is very experienced," he said. "He likes to train and is having his laughs.

"We don't have any updates regarding his situation."

Meanwhile Hiddink insists there has been no bid from China for midfielder Oscar. "We and I think the club doesn't know anything about this so we are not going into speculation," he said.