Unseeded Pella failed to win either of his previous ATP World Tour finals, losing in Rio and Munich in the past two years.

His 6-3 1-6 6-2 victory over Haase set up a meeting with Marco Cecchinato, the French Open semi-finalist having cruised past Marco Trungelliti in straight sets.

Cecchinato only needed 66 minutes to dispatch Trungelliti 6-2 6-1, reeling off 11 successive games to end the Argentine qualifier's dreams.

Monday's (AEST) final on American grass in Newport will see Steve Johnson face Ramkumar Ramanathan at the Hall of Fame Championships.

Johnson maintained his 100 per cent record against Marcel Granollers with a 6-3 6-3 victory, his third successive victory over the Spaniard.

Ramanathan's sensational run in Newport has seen him dispatch Victor Estrella Burgos, Denis Kudla and Vasek Pospisil on his way to the last four.

Tim Smyczek was also brushed aside as Ramanathan reached his first Tour final, the Indian winning 6-4 7-5.