Arsenal are prepared to sell and currently want €20m to part with the 22 year-old.
Benfica rate Guendouzi closer to €10m, though are willing to go higher with club chiefs convinced by the talent and potential of the youngster.
With Hertha, Guendouzi had a mixed campaign, winning praise for his performances at times, though also criticism for some ill-discipline.
The midfielder managed 24 appearances with Hertha this past term, scoring twice and producing three assists. He has a deal with the Gunners to 2022.
- updated June 22