Alexander Zverev won the Hamburg Open while Taylor Fritz was crowned Atlanta Open champion in Sunday's ATP action.
Taylor Fritz brought an end to Stefanos Tsitsipas' winning streak at the Monte-Carlo Masters by defeating the defending champion in the quarter-finals.
Alexander Zverev declared his Australian Open campaign already a success after claiming his first top-level victory since suffering a horrific injury last year.
Rafael Nadal said he was slow and rusty as he suffered a disastrous start to his bid to win the ATP Finals for the first time after crashing to a 7-6 (7/3), 6-1 defeat to Taylor Fritz on Sunday.