Costa saga looms over Chelsea's Atletico Champions League showdown
Chelsea club ambassador Paulo Ferreira feels it is difficult to answer which club Diego Costa will be contracted to when the Premier League champions face Atletico Madrid in the Champions League.
Antonio Conte's men were placed alongside Atletico, Roma and competition debutants Qarabag in Group C in Thursday's draw.
Costa was the Blues' top scorer on the way to glory last season but has subsequently been exiled by Conte.
The Spain striker has repeatedly voiced his desire to re-join Atleti, who he left to move to Stamford Bridge in 2014.
Ferreira, a two-time Champions League winner with Porto and Chelsea, was reluctant to be drawn on a complex situation.
"Of course, it is a difficult question to respond to but the most important thing is Chelsea being in this competition," he told BT Sport.
"For sure it will be a tough game, the same as Roma and Qarabag. We will do our best to go forward in this competition."
The 2012 winners are back in Europe's top competition after a shambolic Premier League title defence in 2015-16 left them without continental fixtures last term – a state of affairs Ferreira feels it was tough for Chelsea to accept.
"It's so good to be back again in this competition," he said. "It was quite strange for a club like Chelsea to be out of the Champions league. It is not good.
"A club like Chelsea, when you enter this kind of competition it is to go as far as you can and try to win.
"All the top clubs here are looking for that and Chelsea are a top club.
"Everything is possible. It will be hard but we will do the best we can."