Di Matteo: Terry out for three weeks
Initial fears that the injury, sustained in a collision with Luis Suarez, could be long-term have proved unfounded and Terry should be back well before the busy Christmas schedule.
"With Terry, we're looking at approximately three weeks out; fortunately it's not as bad as we first thought," Di Matteo said at his news conference ahead of their Saturday trip to his former club West Bromwich Albion.
"On one hand we are pleased but on the other we are disappointed that he was just back and we lose him again.
"He was looking sharp and it gave the team a lot of confidence so it was unfortunate for us to lose him in his first game back."
"He is an important player for us and it is a crucial time of the season so that is a shame," added the Italian.
Terry, who has a ligament strain, was playing in his first league game since completing a four-match FA ban for racially abusing Queens Park Rangers defender Anton Ferdinand.
Chelsea are also without fellow centre-back David Luiz who has tonsillitis and midfielder Frank Lampard as he continues his recovery from a calf strain.