Chelsea interim manager Guus Hiddink admits Diego Costa's suspension leaves him with a big problem ahead of the visit to Manchester United. Costa, 27, scored twice in a much-improved performance in the 2-2 draw with Watford on Saturday 26 December in what was Hiddink's first game in charge following the departure of Jose Mourinho.

The Spain international marred the afternoon somewhat when he picked up his fifth yellow card of the season with two minutes of the game remaining, ruling him out of Monday's meeting with Louis van Gaal's side.

Chelsea have Loic Remy and Radamel Falcao in reserve to fill the void up front but speaking after Saturday's draw, Hiddink admitted he is still to make a decision on who will play. "He is out for United, with a fifth [booking], which means we have to think how to solve that problem," Hiddink told reporters. "It's a pity because he'd put in a good performance. So we need to solve that problem in the next 48 hours."

Costa had endured a relatively disappointing season prior to Saturday having scored just four goals in 21 games until the visit of Watford. Hiddink hopes the reinvigorated striker can continue to make up for lost time.

"[Costa] focused himself where he's good, and there he's very dangerous," Hiddink added. "That's important. He's not wasting extra energy where he shouldn't, and he did that."

The Blues travel to Old Trafford on Monday 28 December with both sides coming into the contest in woeful form. Chelsea have won just one of their last five games while United suffered their fourth defeat on the bounce to Stoke City on Boxing Day and are without a win in seven.

United's slide has left Louis van Gaal's position as manager under real doubt but the Dutchman says he could still decide to jump before he is pushed.

"I can also quit by myself," van Gaal told reporters. "That is something I speak to Ed Woodward [about] by himself -- not with you.

"It is not always [that] the club has to fire or sack me. Sometimes I do it by myself. I am the one who wants to speak first with the board of Manchester United and with my members of staff and players -- and not with you."