Mischa Zverev took some of the limelight back from younger brother Alexander when he beat second seed Kei Nishikori to reach the Geneva Open final on Friday.
The German, whose younger sibling Alex won the Italian Open last week to reach No 10 in the rankings, produced some dazzling serve-and-volley tennis to beat Nishikori 6-4 3-6 6-3.
Moscow-born Zverev, ranked 33, will face home favourite Stan Wawrinka in the final. The top seed beat Russian Andrey Kuznetsov 6-3 7-6(4).
Zverev, 29, stunned the tennis world at the Australian Open when he beat World No 1 Andy Murray before losing to eventual winner Roger Federer.
The last time he reached an ATP Tour final was in 2010, when he was beaten by Frenchman Gilles Simon at the Moselle Open.
Second seed Tsonga served 14 aces to reach the 26th final of his career, and his first on the red dirt, where he will face Tomas Berdych after the Czech defeated top seed Milos Raonic of Canada 7-6(5) 7-6(2).
Tsonga got off to a poor start in the claycourt season, withdrawing from his second-round match at the Madrid Masters before skipping the Rome Masters with a shoulder injury.
In the other semi-final, third seed Berdych avenged his Rome third-round defeat by Raonic by playing better in the two tie-breaks to get a chance to claim a 14th ATP title – his first this year.