According to Sport, the La Liga side are prepared to pay €100m for the 20-year-old France international this week.
The two clubs now have an outline for an agreement, though are still to agree on bonuses for the striker.
The German side are seeking an extra €30m to be paid by Barcelona based on appearances and success for Dembele. Nonetheless, Barca president Josep Maria Bartomeu views the demands as excessive.
The Spanish club, reportedly, are pushing for a straight €100m deal.