Alexander Zverev had to dig deep to stay in the Shenzhen Open, but hopes of a semi-final with his brother came crashing down as Mischa bowed out.
The German siblings have previously met twice on tour with older brother Mischa prevailing, but a third encounter - and first since 2014 - will not happen just yet.
Mischa - the third seed in China - fought back from a set down against Dudi Sela to force a decider, but his efforts used up all his energy as Sela raced to a 6-3 5-7 6-2 win.
There looked like being another Zverev departure when Steve Darcis led 4-2 in the third set against Alexander, but the world number four learned from his brother's mistakes.
The top seed broke in the seventh game before levelling things up, and in the tie-break the 20-year-old kept his nerve despite falling 5-2 behind, Alexander reeling off five successive points to win 4-6 7-6 (7-5) 7-6 (7-5).
He will meet Damir Dzumhur in the last eight after he eased past qualifier Lukas Lacko, the sixth seed winning 6-4 6-3.
Thursday's final match saw Alexandr Dolgopolov get the better of Sergiy Stakhovsky in an all-Ukrainian clash.
Dolgopolov set up a quarter-final with Sela thanks to a 7-6 (7-5) 6-4 over his compatriot.
In Chengdu, top seed Dominic Thiem's quest for a second title of the season ended in the second round as he was beaten by Guido Pella.
Thiem won four tournaments last year but has only been a champion once in 2017 - in Rio de Janeiro - and hopes of adding to that in China were swiftly cut short.
In just under two hours, Pella sealed a 7-6 (8-6) 6-4 victory, setting up a last-eight clash with qualifier Taylor Fritz - the American having seen off Nikoloz Basilashvili in three sets.
Marcos Baghdatis is also into the quarter-finals after coming from a set down to beat Peter Gojowczyk 5-7 6-3 6-2.
His reward is a meeting with Lu Yen-hsun, the world number 63 having comprehensively ditched fourth seed Andrey Rublev 6-2 6-1 in just 53 minutes.