Former Chelsea boss Roberto Di Matteo believes that Nemanja Matic has become an "integral part" of Jose Mourinho's side.
The 26-year-old scored the only goal of the game to guide the Blues to a 1-0 victory over Sporting Lisbon in their Champions League clash.
Di Matteo feels that the Serbian has become crucial to Chelsea's success since rejoining the club from Benfica in January.
He told Sky Sports News: "He's been very impressive. There might have been a few doubts about his signing, with him coming back to the club, but he's really impressed everybody within the team and all the supporters.
"He dictates the time of the team, he shields the back four very well and he has great distribution with his left foot. He has good vision as well. He's matured very well as a player.
"I remember when he left, when he was a little younger, but he's become an integral part of this team."
Mourinho's side face Arsenal in their Premier League showdown on Sunday.
