Former Chelsea star Dan Petrescu rates his old club favourites in their Europa League tie with Rubin Kazan.
But the Dynamo Moscow coach insists 'Ruby' is capable of an upset.
"Of course, Chelsea is favourite in the fight for the semi-finals of the Europa League. But the Londoners could face serious problems.
"Ruby is a tough nut, which has repeatedly pulled off upsets and can beat any opponent.
"They've been a stable team for many years and has shown with their football they can provide a big problem to opponents."