Chelsea are ready to make a late bid to sign Sevilla defender Jules Kounde. The Blues were all set to sign the French defender but were deterred by Sevilla's late demands.Talks between Sevilla and Chelsea have been ongoing all summer. The Spanish club initially wanted the Blues to match Kounde's release clause of £68 million.However, after weeks of negotiations, the two clubs settled on a fee in the region of £42 million for the player. Chelsea left the deal hanging to prioritize the signing of Romelu Lukaku and the sale of Kurt Zouma.After seven-and-a-half years with the club, Kurt Zouma leaves Chelsea for West Ham.Wishing you all the best for the future, @KurtZouma. 🤝— Chelsea FC (@ChelseaFC) August 28, 2021While both of those deals have gone through successfully, Sevilla have now changed their stance on the previous verbal agreement with Chelsea.They are demanding Chelsea to pay £15m more on the previously agreed fee if the Blues want to sign Kounde. The player himself is keen on a move to Stamford Bridge and was left out of Sevilla's weekend matchday squad in anticipation of an impending transfer.Chelsea had a complicated and tense day for Jules Koundé negotiations with Sevilla. Deal on the verge of collapsing many times but... today Chelsea will try again with final approach. Sevilla are so strong on their position. 🔵 #CFC #DeadlineDaySaúl deal now completely blocked.— Fabrizio Romano (@FabrizioRomano) August 31, 2021Why are Chelsea so eager to sign Kounde?Sevilla feel they are on the right because Chelsea have left them with very little time to complete a replacement signing. The transfer window is set to shut on August 31.As for Chelsea, the Blues are upset with Sevilla going back on their word. According to reports, the deal has been on the verge of a collapse several times over the last 24 hours.However, latest sources are confirming that Chelsea are ready to try and make one last bid to see if Sevilla will sell Kounde. Although no numbers have been mentioned, it can be expected that Chelsea will not match Sevilla's late demand of £57m.Chelsea have sold Kurt Zouma to West Ham United and Davide Zappacosta to Atalanta. This means the club are one defender short of having perfect cover for their five starting defensive players.Chelsea are also chasing Atletico Madrid midfielder Saul NiguezChelsea are also in the race to sign Atletico Madrid midfielder Saul Niguez. The deal is stuck on a knife's edge at the moment. Although initial terms have been agreed to transfer the player on a season-long loan deal, the problem is with the second half of the agreement.Chelsea want to include an "option-to-buy" while Atletico are keen to add an "obligation-to-buy" term for the Spanish midfielder. With only a few hours left before the transfer window shuts, anything can happen on deadline day.