Chelsea face a major challenge to bolster their squad ahead of the close of the transfer window, after Everton insisted they would not part with John Stones. The England international center-back has been the subject of at least three rejected bids, rising as high as £30 million, from Stamford Bridge. But there looked set to be decisive movement in Chelsea’s favor earlier this week when Stones handed in a transfer request. Rather than buckle to the wishes of one of their 21-year-old rising star, however, Everton have reaffirmed their stance that he is not for sale this summer.

“Everton Football Club has rejected a transfer request from John Stones,” chairman Bill Kenwright said in a statement on Everton’s official website. “Since the start of the transfer window, we have resolutely turned down offers from another Premier League football club for our player. John is not for sale and he will remain a highly valued member of our first team squad.”

It remains to be seen what Stones’ or Chelsea’s response will be to Everton’s stance. But Stones did start for Everton in their League Cup tie at his former club Barnsley on Wednesday, even after handing in his transfer request. While Chelsea could yet test Everton’s resolve with an even larger bid, it is also likely that they will now be making contingency plans.

Given the struggles of his defense, notably veteran captain John Terry, early in the season, Chelsea manager Jose Mourinho appears to have made strengthening that department a priority late in the transfer window. Already earlier this week there were reports that the Blues had identified Zenit St Petersburg’s Ezequiel Garay as an alternative.

Yet Chelsea have again encountered a far from straightforward path to his signing, with the Russian champions knocking back an initial approach. Garay, 28, only joined Zenit form Benfica 12 months ago. The former Real Madrid center-back is a regular for Argentina and is gifted with the ball at his feet, although, like Terry and, to a lesser extent, Gary Cahill, he is lacking in pace. Still, ESPN reports that Chelsea will continue their pursuit of Garay, and are confident of getting a deal done, if signing Stones becomes an impossibility.

Even if Stones were to arrive, reports suggest that Chelsea are lining up an even bigger deal before the close of the transfer window next Tuesday. The Independent, is among various outlets, reporting that Chelsea believe they can persuade Juventus to part with French midfield star Paul Pogba with an offer of £70 million.

Pogba has been sporadically linked with Chelsea and several of Europe’s other top clubs throughout the summer after a season in which he helped Juventus reach the Champions League final. Indeed, the 22-year-old’s stock has consistently risen since he departed Manchester United for Turin three years ago. And at Stamford Bridge he could well be seen as the solution to the dilemma of how to balance their midfield.

But, while Juventus have previously suggested they may be compelled to sell Pogba should a mammoth offer arrive, that now looks an extremely unlikely prospect in this window. With the Italian champions having already allowed two key midfielders to depart -- Arturo Vidal and Andrea Pirlo -- they can ill afford to lose a third. Indeed, Sky Italia journalist Fabrizio Romano is among those in Italy convinced that there is no prospect of Pogba being sold.