The duo were roommates together at Arsenal when Fabregas first joined the Gunners, and the Swiss has admitted that the midfielder picked up the English language and life in the Premier League very quickly.
Senderos also believes that the Spaniard has had a brilliant career and will only continue to improve with the Blues.
He told the Birmingham Mail: "It is a long friendship. He didn't speak a word of English when he moved to Arsenal. I was next to him and trying to help him in everything he needed. But he picked it up pretty quickly.
"He is a terrific player. He speaks on the pitch better than anyone. I'm pleased for him that he is doing well at Chelsea. His dream was to go back to Spain and play for Barcelona in his hometown.
"But he also now has a fantastic environment where he can develop at Chelsea. He is really happy."
Villa take on Chelsea in their Premier League clash on Saturday.