The Black Cats are the first side to prevent the Blues from scoring in a frustrating draw for Mourinho's men.

Yesterday, Sunderland did what no team so far in the Premier League has been able to do against current league leaders Chelsea this season. The Black Cats, who also were the only side to beat the Blues at home last season, successfully prevented Jose Mourinho's men fom scoring on Saturday--an impressive feat considering that they boast the most prolific offense in the league with 30 goals from their previous 12 games.

So while Gus Poyet's side continue to be a tricky opponent for Chelsea, the match was not without controversy. New signing Diego Costa, who is currently battling with Manchester City star Sergio Aguero for the Premier League's top scorer has hit the ground running since arriving in England. However, the Brazilian-born Spanish striker has already gotten people talking with some of his antics on the pitch, and the trip to the Stadium of Light was no exception.

The first incident saw him mixing it up with John O'Shea after the defender brought him down with a hard tackle by seemingly kicking out at the Irish international and team captain, yet no warning was given. This was then followed up by hitting vice-captain Wes Brown with a trailing arm as the two engaged in an aerial battle, which saw the former Atletico Madrid star booked.

Costa was booked for this tussle with Brown, but saw nothing for the incident with O'Shea

As a result, he will miss out on Chelsea's meeting with Tottenham, but Mourinho saw nothing wrong in his player's combative approach...and implied Brown was the instigator in the incident.

"Why are you always talking about Diego? I don't agree [that his style is becoming a problem]," he stated to the BBC after the game.

"[Wes] Brown is very experienced and [knows] how to use his body. [Player like him] can frustrate a striker and also be clever enough to [get them] carded."

Nonetheless, the Portuguese tactician does not believe that Costa's absence will hurt his team too much as both Loic Remy and Didier Drogba are available.

Interestingly, Sunderland's Poyet did not entirely disagree with the decision that saw Costa only earn one yellow card and even praised the new signing's performances so far this season.

"That's Diego, always on the line, close to the limit. The first one with John O'Shea, there was a little bit of a situation in there," he commented.

"Those decisions go one way or the other. But I'm pleased that he is going to be able to play because he's the best striker in the league and you want to see him week in, week out."