Costa has adapted seamlessly to life in the Premier League following his £32 million ($53.1 million) move from Atletico Madrid in the close-season and the Spain international took his goal tally to seven from just four matches with a hat-trick in Chelsea's 4-2 win over Swansea on Saturday.
Blues boss Mourinho is delighted with Costa's predatory finishing and combative style, but he believes the probing passes of Spain midfielder Fabregas have been just as instrumental in the Brazil-born star's success.
Mourinho's decision to bring Fabregas back to the Premier League in a £27 million switch following an underwhelming spell at Barcelona is also paying early dividends, with the former Arsenal playmaker providing assists for two of Costa's goals against Swansea.
Now the dynamic duo will take their promising partnership into Europe for the first time on Wednesday when the Blues host Schalke in their opening Champions League Group G fixture and Mourinho expects Costa to benefit from more Fabregas magic against the German club.
"To play with Fabregas is the dream of every striker," Mourinho told Chelsea TV.
"The guy sees the movement, sees the pass, is not selfish, makes always the right choice."
Mourinho's praise must be music to Fabregas's ears but, publicly at least, he was keen to play down his own contribution when asked about his form and the link to Costa's flying start.
"Just trying to do my job
That's it," he said.
"We have a good team, strong, young, with a lot of courage
We showed it again against Swansea."
- Defensive malaise -
After bemoaning Chelsea's lack of cutting edge for much of last season, Mourinho has no complaints about the brilliant attacking play which has brought 15 goals in four games as the Blues raced to the top of the Premier League.
Chelsea would love to lay down an early marker in Europe as well after suffering a painful semi-final exit against Atletico Madrid last season.
They are firm favourites to qualify from a group also featuring Sporting Lisbon and Maribor.
But, unusually for a team managed by the traditionally cautious Mourinho, they have conceded five times in the last two games and the former Real Madrid manager admits he is trying to identify the cause of Chelsea's defensive malaise.
"I don't like (conceding), but we were analysing the goals against Everton and trying to identify the mistakes and we'll do the same thing with these two goals (against Swansea)," said Mourinho, who may be without Didier Drogba on Wednesday after the Ivory Coast striker suffered an ankle injury.
"If you score more goals than the opponent you win, but you want to be more consistent behind because it's not possible to always score four, five, six or three.
"There will come a time when we need a point and a 0-0 is a point or we need a victory and 1-0 is also a victory."
Schalke make the trip to west London with a point to prove after losing to Chelsea home and away in the Champions League group stages last season.
Jen Keller's men hardly had the ideal preparation for their revenge mission as they crashed to a dismal 4-1 defeat at Borussia Monchengladbach on Saturday.
That loss meant that for the first time in 46 years Schalke have failed to win any of their first four competitive games of a new season.
Source : AFP
Source: AFP