Alexander Zverev stormed back to beat Filip Krajinovic and reach the German Tennis Championships semi-finals after splitting with coach Ivan Lendl, while Andrey Rublev claimed the scalp of Dominic Thiem.
Zverev and Lendl have parted ways less than a year after starting their collaboration ahead of the US Open.
The German could start the post-Lendl era with a second ATP Tour singles title of the season, having come from a set and a break down to beat Krajinovic 2-6 7-5 6-2 in his homeland on Friday.
Krajinovic served for the match at 5-3 up in the second set, but Zverev showed great resistance to pull himself off the ropes, winning four games in a row to level the match before largely dominating the decider.
Second seed Zverev will take on defending champion Nikoloz Basilashvili in the last four after the fourth seed beat Jeremy Chardy 6-2 6-3 in Hamburg.
Top seed Thiem's titles hopes were ended with a 7-6 (7-3) 7-6 (7-5) loss to 21-year-old Russian Rublev, who will face Pablo Carreno Busta - a 3-6 6-2 7-6 (7-4) conqueror of Fabio Fognini.
Carreno Busta's fellow Spaniard Roberto Bautista Agut was knocked out of the Swiss Open Gstaad by Joao Sousa, a 4-6 6-3 7-5 quarter-final winner.
Pablo Andujar and Albert Ramos Vinolas continue to fly the flag for Spain in Switzerland, though, and will meet at the semi-final stage following defeats of Dusan Lajovic and Roberto Carballes Baena respectively.