Frances Tiafoe downed fellow American Sebastian Korda in a hard-fought encounter to reach the final of the Estoril Open, while Holger Rune reached a first title match at the BMW Open.

Korda had eliminated top seed Felix Auger-Aliassime in the quarter-finals in Portugal to set up an all-American last-four clash, and looked on course to reach the final after winning the first set against Tiafoe.

However, the fifth seed roared back to seal a 4-6 7-6 (7-2) 6-4 victory and set up a final encounter with Argentina's Sebastian Baez, who beat Albert Ramos-Vinolas to reach his second tour-level final.

Baez also needed three sets in his semi-final clash after losing a competitive second-set tie-break, but he then produced a scintillating performance to win the decider without dropping a game, winning 6-3 6-7 (7-9) 6-0.

Elsewhere, Danish 19-year-old Rune sealed his first ATP tour final appearance by beating home favourite Oscar Otte 6-4 6-4 at the BMW Open in Munich.

Rune, who has enjoyed a dream week in Bavaria after sensationally downing Alexander Zverev in the last-16 and failing to drop a single set in the tournament, revealed his ambitions to become world number one in the future after the victory.

"It's a pretty unreal feeling," he said of his semi-final win. "I didn't expect this at all coming into this tournament, and I just took it match by match. Obviously, I had a tough draw, playing Zverev in the second round, but I knew it was going to be tough, so I was ready from the beginning, and I'm super happy to be in the final.

"It's getting better and better, I'm improving every day, and this is what matters. I have some goals to be number one in the world, and you have to start somewhere."

Rune will face eighth seed Botic van de Zandschulp in the final after the Dutchman rallied to beat Miomir Kecmanovic 2-6 7-6 (7-4) 6-4 in his own final-four encounter.