LONDON -- Guus Hiddink says he is impressed by Bertrand Traore's development in recent months at Chelsea and admits the youngster is now his preferred alternative to first-choice striker Diego Costa -- ahead of Loic Remy and January loan signing Alexandre Pato.

Traore was kept at Stamford Bridge rather than being loaned out by former manager Jose Mourinho last summer with a view to featuring in the first team, but he played a grand total of just 30 minutes as a substitute across three matches before the Portuguese's departure in December.

Interim successor Hiddink has given Traore greater exposure with Radamel Falcao a long-term absentee because of a "very serious" thigh injury and Remy plagued by persistent calf problems, and the 21-year-old has responded with three goals in his last three substitute appearances.

Traore is now in pole position to lead the Chelsea line if Hiddink follows through on his suggestion that he may rest Costa against Norwich City on Tuesday or Stoke City on Saturday, in order to keep him fit for next week's Champions League round of 16 second-leg clash with Paris Saint-Germain.

"If I see Traore now compared to when I came in, he was always ambitious," Hiddink told reporters. "He's a very fresh guy and I like his attitude. He's not afraid to make errors and he's not influenced by external circumstances. He's fresh whether there are no spectators [in training at Cobham] or if there are 40,000 in the stadium.

"In terms of the way of playing, we talked and trained with him on where he has to improve, because every young player must know how the game is played. He was overdoing it a bit because he's a very busy, mobile guy, and he was punished several times by strong defenders.

"Now he's coping with that a lot better in recent weeks, which means he's open to learn. You can teach him things and he's very clever to do it."

Bertrand Traore is in line to replace the resting Diego Costa at the front of Chelsea's line this week. ADRIAN DENNIS/AFP/Getty Images

Remy is available for selection again while Pato is considered fit enough to make his debut after a lengthy "preseason" programme of double sessions at Cobham, but Hiddink warns that both will have to compete with the improving Traore and earn their minutes.

"His attitude in training is very good," Hiddink said of Remy. "He's working hard but if young guys are knocking on the door there is competition.

"The impression I have is that he's pushing himself. There were -- and he admitted this himself -- some opportunities before my [arrival] when Diego was out that he was not ready to play, so that was damaging for him.

"He's very aware of the situation and he's now getting fitter and fitter. His attitude is perfect but if a young guy [Traore] is showing what he showed when he came in the games, then I must have fair judgement of who to bring."

On Pato, Hiddink added: "I give my fairness in who I bring [into the team] now, and there will be options for him. I cannot say there will be one or five or six games. Compared to the other's it's a last bit of sharpness [that he lacks], because if you play in the Premier League you must be very sharp or you get punished."