Basilashvili was leading 5-4 in his quarterfinal with Norbert Gombos when it was suspended on Friday due to rain. The Georgian served out the first set on Saturday and broke Gombos once in the second for a 6-4, 6-4 win.
He then blew away Casper Ruud 6-1, 6-2 in the semifinals, breaking the Norwegian five times.
Ruud, too, was playing his second match of the day after beating John Millman 6-3, 6-4. Their quarterfinal was suspended on Friday following the first set.
Basilashvili heads into his second tour final of the season after winning the Qatar Open in March. He has a 4-2 career record in finals, with two of those wins on clay.
Struff made his first tour final after ending a seven-match losing run in semifinals by stopping in-form qualifier Ilya Ivashka 6-4, 6-1. Struff recovered from 3-1 down in the first set, winning 11 of the next 13 games.
At 44th in the world, Struff shed his record of being the highest-ranked men’s player yet to have played an ATP singles final.
Ivashka had beaten two-time Munich champion Alexander Zverev in the previous round and went 10-2 on clay last month.
Basilashvili and Struff are tied 2-2 in their tour main-draw meetings. Basilashvili won their most recent meeting in the Sardegna Open quarterfinals last month, also on clay.