Chelsea striker Radamel Falcao's fitness a concern for Guus Hiddink

LONDON -- Chelsea boss Guus Hiddink admits he is "worried" about Radamel Falcao's fitness situation as the Colombia international continues to struggle in his attempt to return from a persistent thigh injury.

Falcao, 29, flew to Monaco on Tuesday to allow his parent club to assess his condition after aggravating a thigh problem -- first sustained in October -- during a training match at Cobham last month.

The trip fuelled speculation that the striker's season-long loan deal could be terminated in January, and while Hiddink refused to comment on his future at Stamford Bridge, he confirmed that the injury-ravaged player remains "out of sight" of first-team involvement.

"I'm still a bit worried about his situation," Hiddink said of Falcao, who has scored just one goal in 11 appearances for Chelsea this season.

"When I came in he was injured, then he started training again and got a setback, and then I said to give him the time, the rest and the peace to recover well and we'll see. So he's a bit out of sight at this moment for the first team."

Diego Costa remains Chelsea's only fit established striker with Loic Remy training on his own as he battles to recover from a calf injury, although youngster Patrick Bamford could make his senior debut for the Blues in the FA Cup third round against Scunthorpe United on Sunday after cutting short a "terrible" five-month loan spell at Crystal Palace.

Asked if he was prepared to look for internal solutions to his striker shortage, Hiddink replied: "I have had more time also to see and analyse the potential of the young players around 18, 19, and maybe, hopefully, there could be a surprise."