The United States international winger has been their standout player since Chelsea's return from lockdown, scoring twice in the last five games, with his skilful runs causing real problems for defences.
Barkley said: “Since Christian came back from lockdown he has been on fire. He had a couple of little niggles easier in the season - and he didn't have much of break last summer before he joined us.
“So maybe this break has done him the world of good. Since he came back he has been blazing. He has been scoring great goals in training, and now he is doing it in matches.
“He is such a difficult player to defend against, because he is so direct. He is so confident. He is always ready to try and take a player on. He is a real problem for defenders."