According to L'Equipe (h/t Sport Witness), Monaco could seriously consider selling Lemar if Arsenal were to offer €100 million when the transfer window reopens in the winter.
The France international has endured a tough start to the season and has managed just two assists so far, according to WhoScored.com.
Monaco may therefore find it difficult to turn down another large offer, while there is also a suggestion the player could benefit from a change of scene.
Monaco vice-president Vadim Vasilyev has said recently that Arsenal came close to signing the Frenchman last summer, according to Bryan Swanson at Sky Sports News.
He said: "Liverpool were really interested. But it was Arsenal that was really close to finalising the deal. It was quite close. At the same time it was just too late, not enough time, to really follow up on this deal."
Vasilyev also said that Lemar had "a fair chance to an exit next year," but with regards to a move in January he added: "never say never, but this is not what we're thinking of, that is not really in our plans."
Per Telefoot (h/t the Guardian), Arsene Wenger said in September that he would return for Lemar, but it remains to be seen if the Gunners will make an approach in January or wait until next summer.
The Gunners could, however, turn to Silva as a replacement for either Sanchez or Mesut Ozil, according to Alvise Cagnazzo at The Sun.
Arsenal missed out on Silva in the summer, as he moved from FC Porto to AC Milan, but the Rossoneri have had a poor start to the season and currently lie in 10th.
If the club fail to secure Champions League football, they may be forced to sell players in a bid to recoup earnings lost from lucrative sponsorship deals.
Silva cost £33 million and is one of the club's more valuable assets; he is yet to open his Serie A account, but he has scored four Europa League goals already, per WhoScored.com.
His record at international level is also impressive, as highlighted by Squawka:
If Sanchez does depart Arsenal, the Gunners will need to invest in an attacking replacement who can provide goals, and Silva certainly fits the bill.
The 21-year-old is quick, alert and is an excellent finisher who will surely only improve as he matures, although Milan will surely be loath to lose him after just one season.