Diego Costa has reportedly suffered a hamstring injury during a routine Chelsea training session, putting his involvement in Saturday's Premier League fixture against Everton in serious doubt.
Worse than that, The Daily Telegraph reports that there are fears that the Spanish international striker - who moved to Stamford Bridge from Atletico Madrid in a £32 million deal earlier this summer - could miss up to six weeks of the new campaign as a result.
25-year-old Costa has enjoyed a promising start to his Chelsea career, netting two goals in as many Premier League games for Jose Mourinho's side against newly-promoted opposition in the form of Burnley and Leicester City.
With Mourinho having lamented the lack of consistent goalscoring nous from his striking unit on several occasions during a trophyless 2013/14 season, Costa's physicality, determination and ability to find the net on a regular basis is likely to prove crucial to his side's chances of living up to their tag as title favourites this time around.
His absence will leave Chelsea with just two fit senior strikers to choose from moving forward in the much-maligned Fernando Torres and club legend Didier Drogba.
Sky Sports news have recently confirmed that Costa's injury is a 'minor muscular problem', although they did not appear to offer an updated timeline for such an issue.
With the transfer deadline now just days away, it will be interesting to see how this will affect Mourinho's plans and if he will now be intent on securing the signing of another forward while the option still remains.
This news could also have a significant impact on the future of Costa's international teammate Torres.
Having failed to replicate his previously stellar form in West London since a British record £50 million switch from Liverpool back in 2011, Torres has been frequently linked with a move away from the club this week, with speculation suggesting that he is ready to accept a loan offer from Serie A giants AC Milan.
Costa's injury - if it does lead to a lengthy layoff - will surely scupper those plans, even if Mourinho does manage to achieve further success in the transfer market.