guus hiddink
Guus Hiddink already watched the victory over Sunderland from the Chelsea boxGetty

Guus Hiddink, Chelsea's interim manager and replacement for the sacked Jose Mourinho, says the club still can mathematically make the top four this season but he is aware it will not be an easy feat. The Dutch boss was speaking in a press conference ahead of the home game against Watford on Boxing Day (26 December).

The 69-year-old also said he wanted to watch the next few matches before making a decision on whether the squad needs to be improved upon during the January transfer window, while he also claimed he will talk with the club over a potential long-term stay at Stamford Bridge "the end of the season".

"I shouldn't be here halfway through the season. It means things are not going well. But anyhow, I am glad to be back. It is a few years ago I was here in a similar situation," Hiddink said, as quoted by the BBC. "If you look back a bit to last season when there was this year of success, then you go into next season with targets and wins, which are the same: winning the title again. It is not easy after a championship. You relax as a team and get a wake-up call. It is not easy to say that I am here and the problem is solved."

The Dutch manager is optimistic about turning the fortunes of the club around after seeing his side beat Sunderland 3-1 with a convincing performance.

Asked whether the Blues still can make the top four to secure the Champions League qualification, he said: "Mathematically it is possible. If you can add up then it is possible but this league is very strong, which has been especially proven this year with all respect to the clubs at the top – Leicester, Crystal Palace, Watford... it is amazing and refreshing. It means that all the teams can kill each other."

Reports have claimed Hiddink is likely to make some new additions to the squad to improve Chelsea's chances, alongside those stating he is also keen on having Didier Drogba back at the club, with his agent, Thierno Seydi, confirming an offer without specifying what sort of position the Premier League champions had put forward.

Questioned about the January transfer window, Hiddink said: "Let's go into the next few games and we will see. That is always open but first I would like to get through the first few games."

And speaking about Drogba, he added: "I worked with him five or six years ago. I was delighted to have such a professional in the squad. He is a legend already in this squad and outside this club. The only thing is that he is playing in Montreal at this moment."

Hiddink, meanwhile, hopes to get Eden Hazard back to the form he had last season. "He had a terrific season last year and it is normal that you get a little bit of a setback after that," he said. "I think he can be a key player as captain of a national team for Belgium. And he can be a key player here. It's the same with him, he has to be eager to perform."

Chelsea fans voiced their anger at Diego Costa and Cesc Fabregas with boos during the game against Sunderland while also chanting their support for Mourinho. Hiddink said: "I talked to the squad yesterday and we talked about the past a little – why I am here, the reason why we are down.

"But I also told them things happen in football and I want everyone to look themselves in the mirror, for not just a second but for a long time, to see what anyone from now on can contribute to the way up. I emphasised that. And not to look back too much. We cannot ignore what has happened in the recent past but I have asked them to be professionals and see if they can give themselves the best of the team. So I like to look forward.

"I hope the fans will support the team, as they did briefly during the last game. The fans must also think and express themselves about the recent past. The team has to take the initiative. What I know of Chelsea is that the fans back up the team, but the team has to show it first."

And questioned about whether he would like to stay at the club beyond his current contract, Hiddink said: "What we said was 'Let's go to May'. Then we will see."