Costa the final piece in Chelsea jigsaw

The striker scored a fine header and led the line for example on Saturday as Jose Mourinho's side cemented their status as title favourites with a win over Aston Villa

Diego Costa continued his scintillating early season form with a thumping header in Saturday's 3-0 victoryover Aston Villa to notch his eighth goal in six Premier League games.

The Spain international has made light work of adapting to life in
England following a €41 million move from Atletico Madrid this summer.

Question marks remain over the 25-year-old's fitness - Mourinho stated after Saturday's win that the striker is "doing almost nothing" in training due to his hamstring problems - but after another impressive display up front for the Blues, Chelsea's hopes for silverware increasingly look set to rest on Costa's broad shoulders.

PERFORMANCE AGAINST ASTON VILLA

While Costa's strike on Saturday was not decisive in terms of Chelsea collecting three points against Villa, the timing of it - just before the hour mark - allowed Mourinho's men to breathe easy and ultimately stroll to victory at Stamford Bridge.

The home supporters were beginning to grow restless that the Blues had not added to Oscar's early finish, and they had every right to be nervy given Villa's impressive early season form and speed on the counter - but Costa put paid to those worries with a perfectly-timed run and header.

The Spaniard can seemingly do no wrong at the moment as he leads the Premier League goalscoring charts by three goals, but perhaps more impressive than his headed effort was his willingness to drop back and get involved in his side's build-up play to leave his markers chasing thin air.

An attacking midfield trio of Oscar, Willian and Eden Hazard is tricky to track at the best of times, though Costa often traded positions with Oscar in the first half, allowing the young Brazilian to lead the line in order to make late runs into the box.

Costa's influence grew throughout the match and after more fine build-up play 10 minutes from the end, his powerful run and shot forced a defensive mix-up from which Willian gleefully tapped home Chelsea's third of the afternoon.

The forward was withdrawn soon after as Mourinho sought to carefully manage his temperamental hamstring, but Costa looks the real deal. Not since Didier Drogba's glory days has the Portuguese coach had a striker with such a fearsome all-round game, and Mourinho may have found the final piece of his Chelsea jigsaw.

COSTA'S SEASON SO FAR

What more can you really say about a striker who has scored eight goals in his first six games in a new division? The pressure was certainly on Costa following a dire World Cup with Spain, but the 25-year-old has picked up where he left off for Atletico Madrid and is scoring for fun this term.

Chelsea made a difficult start at newly-promoted Burnley on the opening day of their 2014-15 campaign as Scott Arfield put The Clarets 1-0 up 14 minutes in, but it took Costa just three more minutes to turn things round and announce himself as the Blues built on his equaliser to win 3-1.

A second-half strike from Costa made the breakthrough against a dogged Leicester side to help secure another victory, while two more goals at Everton - along with a heated confontation with Seamus Coleman - ensured Chelsea left Goodison Park with three points along with a few more enemies.

A hat-trick then followed as Costa blew away a dangerous Swansea side at Stamford Bridge, while the fact that a draw at Manchester City is both the only league game in which Costa has not scored and also the only one where Chelsea have failed to pick up three points, will not have been lost on supporters.

As Mourinho said after the victory over Villa, Costa's team-mates can "associate" themselves with the striker far more easily than with Torres. With the 25-year-old on form, Chelsea are putting teams to the sword, with nearest goalscoring rivals Man City (12) lagging seven strikes behind Mourinho's men (19).

WILL HE EVER REACH FULL FITNESS?

Quite simply, not even Mourinho and his coaching staff will have an accurate gauge of Costa's fitness until the day before a game at this stage. The Portuguese coach says the striker could be "top" for club and country should Spain refuse to call him up for their next Euro 2016 qualifiers in October, though Mourinho admits Vicente del Bosque will have the final say in that regard.

With Costa barely training at the moment, two games in the space of four days - with a flight in between - may be too soon to risk him against Sporting Lisbon on Tuesday, though Chelsea's home draw against Schalke in the opening game of their Champions League group ensures Mourinho can ill-afford any more slip-ups in Europe.

With both Didier Drogba and Loic Remy waiting in the wings, the Blues could well rest their star man and give him further time in order to be fit for next Sunday's big league clash against potential title rivals Arsenal. Whether that affects their European hopes is up for debate, but until Costa gets those 15 vital days to fully recover, the striker's fitness will be a constant guessing game for both the club and player.