Britain's Andy Murray reached his first tour-level final on grass in six years as he beat Nick Kyrgios in straight sets at the Boss Open in Stuttgart.
His last ATP Tour title came at Antwerp in 2019, while he has not contested a tour-level final on grass since winning Wimbledon for a second time in 2016.
Berrettini, beaten Wimbledon finalist last year, overcame German Oscar Otte.
The world number 10 won 7-6 (9-7) 7-6 (7-5) and will face Murray for the first time since winning in straight sets in the second round at Queen's last year.