10 Biggest Questions Surrounding Chelsea's Title Bid

2. Will Diego Costa Hit The Ground Running?

Diego Costa has enjoyed a terrific pre-season campaign, looking increasingly deadly with each passing game and culminating in his first two goals in front of a Stamford Bridge crowd at Real Sociedad last Tuesday. Chelsea have been in desperate need of a goalscorer and the club's outlay of £32 million to get their man shows a great deal of confidence that Costa is the one to finally provide a clincal spearhead to Chelsea's attack. The big question, then, is how long it will take Costa to adapt to the faster and more aggressive pace of the Premier League. The naturalised Spaniard has the speed and physique to take on the challenge with ease, but Mourinho will need him to keep his bedding in period to a minimum in order that no ground is lost to the likes of Man City in the early stages of the season. Costa may find it more difficult facing sides playing deep when much of his prowess has come from an ability to make runs into space behind the last defender, potentially drawing out the time it takes him to get back to the goalscoring heights that saw him notch 36 goals last season for Atletico Madrid. Mourinho's system may also need some adapting, of course, having become used to working around the limitations of Fernando Torres and Samuel Eto'o, who were more helpful in the buildup to goals than in scoring them themselves. There's every sign that Costa will adapt just find to the demands of his new league, but if he struggles, Mourinho won't be relishing the prospect of having rely on the ever-hopeless Torres or a 36-year old Didier Drogba.