Germany's Alexander Zverev reached his first Grand Slam final in the most difficult manner after fighting back to beat Spain's Pablo Carreno Busta in a tense US Open five-setter.
Fifth seed Zverev, 23, looked lost as Carreno Busta played smartly and precisely to race into a two-set lead.
But Zverev showed incredible resolve to turn the match around and win 3-6 2-6 6-3 6-4 6-3 against the 20th seed.
Zverev will play Dominic Thiem or Daniil Medvedev in Sunday's final.
Austrian second seed Thiem, 27, faces Russian third seed Medvedev - who lost to Spain's Rafael Nadal in last year's final - in Friday's second semi-final at Flushing Meadows.