Fernando Llorente and Olivier Giroud hold the key to Arsenal completing their move for Pierre-Emerick Aubameyang in a complex late deal which would see the current Tottenham Hotspur striker move to Chelsea and Giroud join West Ham United.
Arsenal have already agreed a deal worth around £60m to sign Aubameyang but Borussia Dortmund will only sanction the move if they are able to sign a replacement before the transfer window closes on 31 January.
Michy Batshuayi has been identified as their number one priority but, again, Chelsea will only let him go if they can sign a new forward to compliment Alvaro Morata before Wednesday's deadline.
Reports in recent hours have claimed that Giroud could be the solution to both deals as the Blues are keen on signing the France international, who is keen to make the move to Stamford Bridge in order to increase his chances of playing in the World Cup next summer.
However, the Gunners do not want to sell another player to a direct rival in a transfer window in which they have already sold Alexis Sanchez to Manchester United.
Regardless, Chelsea are continuing to test Arsenal's resolve as the board see the 31-year-old forward as a perfect fit to provide competition for Morata.
But with Arsenal said to be demanding around £30m to cash in on their player, Antonio Conte has asked the Blues hierarchy to make one last effort to sign his long-term target Llorente from Tottenham.
Conte coached the Spaniard at Juventus and has tried to bring him to Chelsea in each of the last two transfer windows.
Chelsea failed to convince Swansea City to part ways with him last January before being beaten to his signing by Tottenham in the final days of the summer transfer window last August.
The Blues are expected to make a final push for Giroud on Tuesday [30 January] and Conte would be happy to welcome the Frenchman to Stamford Bridge as he would be eligible to play in the Champions League.
However, the Italian would still rather Chelsea sign Llorente as he believes that his former Juventus star won't need any time to adapt to his demands. Furthermore, the towering striker previously played with Morata during their spell together with the Serie A giants and has a good relationship with Chelsea's other four Spaniards in Cesar Azpilicueta, Willy Caballero, Marcos Alonso and Pedro.
Chelsea previously made an enquiry to sound out the availability of Llorente earlier in the winter transfer window and IBTimes UK understands that they have made a new approach to Tottenham in recent hours.
The possibility of bringing Giroud in has not yet been completely ruled out by Chelsea but the Blues understand that luring Llorente away from Tottenham would be easier and cheaper than convincing Arsenal to part ways with the Frenchman, given the striker has barely played for Mauricio Pochettino since his £12m summer arrival from Swansea.
Llorente's arrival would also serve to improve their current tense relationship between the Chelsea board and Conte and will also help them save money for a player who is just one year older than Giroud.
Earlier in the window, there were discussions between Chelsea and Tottenham over a swap deal between Llorente and Batshuayi. However, the Blues did not want to lose the Belgium international on permanent basis with the former Marseille star reluctant to go to Spurs to serve as a mere back-up for Harry Kane.
Meanwhile, West Ham are also keeping a close eye on both situations with David Moyes also keen on bolstering his attack with a player like Giroud.
The Hammers have already made an approach to sound out his availability with the hope that Arsene Wenger would rather to sell the Arsenal striker to them than to Chelsea.
If negotiations between the clubs progress, the Frenchman could have the final say on the move as he looked determined to join Chelsea and have a role to play in their Champions League campaign.
One way or another, negotiations between all the clubs are ongoing and an enormous quadruple operation that takes Aubameyang to Arsenal, Batshuayi to Dortmund, Llorente to Chelsea and Giroud to West Ham cannot be ruled out at this stage despite their being less than 48 hours remaining before the transfer window slams shut.
But should one deal fall through, it could have a domino effect and potentially scupper the other three with little margin for error ahead of deadline day.