However, according to Sky Sports' Kaveh Sohekol, Arsenal are ready to make another effort to get the midfielder, with Manchester City chasing Sanchez:
The Telegraph's James Ducker reported Monaco and Arsenal agreed a fee, but Lemar still must decide if he will go.
It's been reported by Sky Sports' Guillem Balague there is hope from Arsenal's perspective that a deal for Lemar can be done:
It had previously been reported by Solhekol that Monaco were seeking to earn around €100 million (£92 million) from any potential sale of Lemar. According to Sami Mokbel of the Daily Mail, the Gunners have made an offer in the region of £90 million for the 21-year-old.
It's an amount that would far outstrip the £60 million that would potentially be picked up from the sale of Sanchez.
According to Sky Sports News, though, Arsenal would not be willing to accept a straight cash offer for their star forward.
As noted in the piece, Raheem Sterling has previously been tipped as a potential makeweight in the deal. But Balague suggested those stories are wide of the mark, with City boss Pep Guardiola keen to keep the England international at the club:
If the Gunners were able to do a deal for Lemar at this late stage of the window, then perhaps they would consider letting Sanchez leave.
After all, the Monaco man also operates off the left flank, too. Lemar is much more of a midfielder in style compared to Sanchez, though.
He's an exciting prospect, and in terms of longevity and talent, he may well be worth the type of money mentioned.
Football writer Andrew Gibney believes Arsenal shouldn't have left their move so late for the Monaco man:
Convincing the French champions to sell at this point in the campaign will be a massive challenge for the Gunners, especially given they have already lost key men this summer in the form of Tiemoue Bakayoko, Benjamin Mendy and Bernardo Silva. Additionally, Lemar is on international duty with France, who face the Netherlands in a 2018 World Cup qualifier on Thursday.
Sanchez's departure would leave a huge void at the Emirates Stadium and supporters disappointed. Lemar's arrival would help fill that gap to a degree and give the fans a bright future to look forward to if their attacking talisman was sold.
You sense a deal will need to be agreed for the latter before the former gets the switch he's seemingly keen on.