Top seed Rafael Nadal swept past Argentina's Juan Martin del Potro in brilliant style to set up a US Open final against Kevin Anderson.
The Spaniard won nine games in a row at one stage on his way to a 4-6 6-0 6-3 6-2 victory in the second semi-final.
Nadal, 31, will try for a third US Open and 16th Grand Slam title on Sunday, against a surprise opponent.
South Africa's Anderson, 31, beat Spaniard Pablo Carreno Busta 4-6 7-5 6-3 6-4 earlier on Arthur Ashe Stadium.
At 32 in the world, Anderson is the lowest-ranked player to reach a major final since the ranking system was introduced in 1973.