Thibaut Courtois, Eden Hazard or Diego Costa: Which Chelsea star can Antonio Conte not afford to lose this summer?

As Manchester United have found out over the years, being top of the Premier League counts for little when Real Madrid come calling for your best players.

Sir Alex Ferguson lost the likes of David Beckham, Ruud van Nistelrooy and Cristiano Ronaldo to the Bernabeu, and Antonio Conte may face a similar battle with his Chelsea squad this summer.

The upcoming presidential election at the Bernabeu brings with it all the usual transfer bluster, with Florentino Perez likely to welcome talk of him seeking a Galactico signing or two to boost his campaign.

Zinedine Zidane has often spoken of Eden Hazard in glowing terms, with the Belgian winger finding form and fitness with 11 goals and four assists this season following a disastrous Premier League title defence last term.

Hazard is now approaching the levels which saw him win the 2015 PFA Player of the Year award.

While Standard Sport understands Chelsea have no intention to sell the 26-year-old - with the winger also committed to staying at Stamford Bridge - Madrid may intensify their approach as Perez has promised a statement signing.

Fellow Belgian Thibaut Courtois has also been linked with a return to the Spanish capital after three successful seasons at Atletico, with Real targeting him as their long-term No.1 goalkeeper with Keylor Navas making blunders and David De Gea continuing to elude Perez's clutches.

Courtois quickly became first-choice at the Bridge under Jose Mourinho, and he too insists he sees his future at Chelsea rather than back in Madrid.

But one man who has suggested that Hazard and Courtois would find it difficult to reject the likes of Real and Barcelona is, funnily enough, Chelsea team-mate Diego Costa.

The striker failed to secure a huge transfer to Chinese Super League side Tianjin Quanjian in January, but neither Conte nor 17-goal Costa have mentioned anything concrete about the Spaniard staying in west London beyond the end of the season.

Costa's former club Atletico have always remained keen on re-signing him - especially if Antoine Griezmann moves on this summer - although Costa has also talked up a potential move to Ligue 1 in recent days.

Standard Sport understands that Conte has been promised significant funds to rebuild his squad with four key signings this summer despite the title looking likely, but that won't stop the likes of Real coming after the Premier League's finest once again.

If push came to shove, who would Chelsea find hardest to replace? Vote in our poll below...