A knee complaint that has troubled Marin Cilic since Monte Carlo last month has forced the Croatian to withdraw from the Madrid Open.
The Estoril Open staff had to be on their best behaviour in front of Portugal's president, while newly married Marin Cilic fell in Istanbul.
It was a routine win in the quarter-finals of the Prague Open for Petra Kvitova, who now faces Zhang Shuai in the last four.
The first clay-court outing of Serena Williams' season will not come at the Madrid Open after the 36-year-old withdrew from the event.
Yannick Hanfmann took the first set off Alexander Zverev after a lengthy tie-break in Munich, but the top seed duly asserted his authority.
There could be a home winner of the WTA's Prague Open after Petra Kvitova progressed in the Czech Republic.
Having re-hired his former coach and fitness trainer, Novak Djokovic says he is free of pain and concentrating on "elevating" his form.
World number two Roger Federer will return to Stuttgart to get his grass-court season under way in the second week of June.
Home favourite Petra Kvitova wasted little time in reaching the second round of the Prague Open, but Dominika Cibulkova bowed out in Rabat.
Rafael Nadal taught Stefanos Tsitsipas a lesson in the Barcelona Open final but the teenager was back in business in Estoril on Tuesday.