The top seed for the men's singles event this year is Carlos Alcaraz and the top seeded women's singles player is Danielle Collins.
Spaniard Carreno Busta eased past Filip Krajinovic in straight sets to win the Hamburg European Open title.
The second seed survived a tie-breaker in the first set before running away with the match in the second to set up a final date with Filip Krajinovic.
Serbian Filip Krajinovic defeated the top seed Greek player in three sets to reach the semifinals of the Hamburg European Open.