Denis Shapovalov and Steve Johnson reached the Delray Beach Open semi-finals as Hyeon Chung faced an exit when the rain hit.
Shapovalov, 18, beat fellow young gun Taylor Fritz 7-5 6-4 in their quarter-final at the ATP 250 event in Florida on Friday.
The Canadian teenager looks on track to make the most of a tournament which has seen almost all of its seeds fall.
Shapovalov took his chances against Fritz, converting both of his break points as the American was unable to take either of his.
His last-four opponent is still unknown after the clash between Chung – the only seed left in the draw – and Frances Tiafoe was suspended due to rain.
Tiafoe was leading 5-7 6-4 5-3 when the encounter was pushed back to Saturday.
On the other side of the draw, Johnson will face Peter Gojowczyk in a semi-final.
Johnson cruised past Evgeny Donskoy 6-1 6-4 and Gojowczyk overcame wildcard Reilly Opelka 7-6 (7-5) 6-3.