Lucy loser Lorenzo Sonego of Italy followed up his shock win over world number one Novak Djokovic by beating Britain's Dan Evans to reach the Vienna ATP final on Saturday.
Sonego had condemned Djokovic to his heaviest best-of-three-set loss in the quarter-finals where the 17-time major winner claimed just three games.
The world number 42, who described that as "the best victory of my life", saw off Evans 6-3, 6-4 and will face red-hot Russian Andrey Rublev in Sunday's final.
"I'm really happy. After yesterday it was not easy playing against Evans because he has a good talent," said Sonego.
"He has a good backhand and it was not easy. But today I won and I am so happy."
Sonego, 25, had initially lost in the final round of qualifying in the Austrian capital to Aljaz Bedene six days ago, but entered the draw as a lucky loser when Diego Schwartzman withdrew.
World number eight Rublev made the final when South Africa's Kevin Anderson retired with a leg injury at 6-4, 4-1 down.
Rublev, chasing a fifth title of this truncated season, has won 18 of his past 19 matches.
"I came here thinking that I have nothing to lose. I already did a really great season, so I came here to enjoy, to do my best, to fight for every point, every match, and now here I am in the final," said the 23-year-old.
"I want to keep thinking in the same way and we'll see what's going to happen tomorrow."
Rublev, the fifth seed, eliminated defending champion Dominic Thiem in the quarter-finals on Friday and has not dropped a set this week.
He has also yet to drop serve.