London - Guus Hiddink admits the absence of Diego Costa is a major blow to Chelsea's hopes of taking advantage of Manchester United's struggles when they travel to Old Trafford on Monday.
Hiddink took charge of his first game since being installed as Chelsea interim manager, overseeing a frustrating 2-2 draw against Watford at Stamford Bridge on Saturday.
The result left Chelsea in 15th place and came at the cost of a fifth booking of the season for Costa, who will now miss the meeting with United while he serves a one-match ban.
The Spain striker had confirmed his value to Hiddink's side by scoring twice against Watford and the Dutch manager said: "It's a setback of course.
"Costa's performances are improving. I can complain (about the booking), but it's not my nature. I have to go on and find a solution as soon as possible."
Loic Remy is expected to step into the line-up for the meeting against United, whose 2-0 defeat at Stoke means they are going into the game without a win in seven matches.
Hiddink acknowledged United are going through a difficult time, but he refused to consider the uncertainty surrounding the future of Old Trafford boss Louis van Gaal.
"Manchester United were first and now they are in a different period. I can't comment on another manager's position," Hiddink said.
Hiddink did, however, express sympathy for the difficulties facing Memphis Depay, the young Holland forward signed by United from PSV Eindhoven during the close season.
"In Holland, Memphis Depay was a star player at a young age," he said.
"He has the talent but is now battling the demands of the Premier League, playing three games a week. These players need the cover of experienced players.
"We will go to Old Trafford, it will be difficult, but I hope this team will show, in every game, the ambition like they showed against Watford - we are going there for the win."