Borussia Dortmund are set to make a decision on Pierre-Emerick Aubameyang's future on Tuesday, says Sky Sports' Spanish football expert Guillem Balague.
Sky in Italy reported earlier this month the Dortmund forward was Arsenal's top target to replace Alexis Sanchez, should he leave the club.
Arsene Wenger has since admitted he expects Sanchez to depart this month - amid interest from Manchester United and Chelsea - and Balague says Arsenal have already begun the process of trying to secure his replacement.
He said: "It's clear that Arsenal are in conversations with the player (Aubameyang) and Borussia Dortmund.
"They think they've convinced the player to join Arsenal, but of course there's still a big obstacle to beat, which is: Borussia Dortmund.
"Arsenal will hear tomorrow if Dortmund are selling cheaply, expensively, quickly, or if they're willing to sell at all.
"Nobody expects this deal to happen early in the week; it may take the whole week, or even more.
"Arsenal are willing to pay 60m euros (£53.3m). They are optimistic - they think this is a deal that could be done."
Aubameyang was left out of the squad for Dortmund's 0-0 draw with Wolfsburg on Sunday, with manager Peter Stoger saying he dropped the 28-year-old after he skipped a pre-match meeting.
Dortmund sporting director Michael Zorc added: "We have only one problem with him - that is punctuality. We have to be very clear about that."