The Ivory Coast international completed his return to Stamford Bridge on a one-year deal last Friday following the expiry of his Galatasaray contract, after originally enjoying an eight-year spell at Stamford Bridge between 2004 and 2012.
Drogba hit 157 goals in 341 appearances during his first stint and is a firm fans' favourite, having scored a late equaliser followed by the winning spot-kick as Chelsea won the 2012 UEFA Champions League with a penalty shootout triumph against Bayern Munich.
The 36-year-old joined Chelsea's squad on Sunday as they defeated Olimpija 2-1 in a pre-season friendly, but did not play a role in the match.
Chelsea boss Mourinho is thrilled to have Drogba back, and claimed it felt as though the forward had never gone away.
"First of all when he came, it looks like he never left the club," Mourinho said after the Olimpija victory. "It was so normal, nothing new at all because he knows everybody and everybody knows him.
"He was ever present even when he wasn't here. Chelsea belonged to him, even in the last two years when he was away playing in a Galatasaray and Shanghai [Shenhua] shirt.
"So it looks like he just went for a short holiday and came back, so everything is normal. But yes, I think we need him. We need him as a player for our squad to be the way I like.
"I like my squad with different qualities, not just as football players but also in terms of personalities. I like to have players with different personalities.
"So as a player and person, Didier is somebody we need to be strong."
