The final of the German Tennis Championships will feature Leonardo Mayer and Florian Mayer after the latter benefited from an unexpected Philipp Kohlschreiber retirement on Saturday.

Leonardo Mayer, who won the title in Hamburg three years ago but only made this year's tournament as a lucky loser after Martin Klizan withdrew, overcame fellow Argentinian Federico Delbonis 6-3 7-5 in the first semi-final.

And namesake Florian then progressed in bizarre fashion when Kohlschreiber brought an abrupt end to their last-four tie while leading by a set.

Having apparently sustained an injury as his opponent held serve for a 3-2 lead, Kohlschreiber thumped his racquet into the ground in frustration before shaking hands with a clearly shocked Florian Mayer and the umpire.

More racquet-smashing followed from Kohlschreiber, who was clearly frustrated at being forced to bring the contest to an end.

Yannick Hanfmann's dream week at the Swiss Open Gstaad continued as the German qualifier saved four match points to beat Robin Haase and reach his first ATP World Tour final.

Hanfmann came from behind to beat sixth seed Haase - a finalist in last year's tournament - 3-6 7-6 (8-6) 7-6 (7-4).

The world number 170 will face Fabio Fognini on Sunday after the Italian also recovered from a set down to beat second seed Roberto Bautista-Agut.