Greek stores will have the option of opening on Sunday, Nov. 29, two days after Black Friday. Retailers are spreading discounts across the long weekend and well beyond it.
Black Friday falls on Nov. 27 this year.
Many Greek businesses now run promotions for days beforehand and keep them going afterward, turning the one-day event into an extended shopping season.
Cyber Monday follows on Nov. 30 and focuses on online sales.
The European Union has warned shoppers to be cautious.
An EU review found that about one in three online retailers mislead consumers during Black Friday, often with inflated "before" prices or false urgency claims.
Under EU rules, a store advertising a discount must show the lowest price it charged in the previous 30 days.
The rule is meant to stop retailers from raising prices just before a sale.