Hiddink's Anzhi host the Magpies in the Round of 16 first leg and the boss of the Russian club believes the French midfielder holds the key.
"It will be very interesting to see how we compare to a side from one of the top leagues in Europe," he told reporters.
"Newcastle did not start the season well, but they have improved a lot in recent weeks.
"They are a strong team that plays modern football. They have powerful and skilful players in every position, such as Moussa Sissoko."