Howe observed Sarri, a coach credited for his organised and entertaining style, during the Italian's time at Empoli.
Speaking ahead of their friendly tomorrow, Howe told the Daily Echo: “It's going to be a real test for us, probably our hardest game of pre-season.
"But it is ideally timed for us to get used to the type of opposition we are going to face week in, week out in the Premier League.
“They are an outstanding team, I would say that.
“It will be a special game. I have a lot of time for their manager, who I have seen work and built a relationship with."