Haas, who ousted No. 1-seeded Jo-Wilfried Tsonga in the second round, eliminated No. 8-seeded Marcos Baghdatis 6-1, 7-6 (7-3) in the quarterfinals. He saved all three of the break points he faced -- all in the second set.
He'll have to beat another seeded player, No. 3 Marin Cilic, to advance to his first final in three years.
Cilic was on the court for 2 hours, 45 minutes before he got past Mikhail Youzhny 6-3, 6-7 (6-8), 6-3. Cilic had 11 aces and lost his serve once in 16 games. That came in the third set but he had two of his three breaks in that set.
The other semifinal pits second-seeded Feliciano Lopez against fourth-seeded Philipp Kohlschreiber. Lopez was a 6-4, 6-2 winner over fifth-seeded Bernard Tomic, pounding out 14 aces and losing just eight points on serve. Kohlschreiber defeated Marinko Matosevic 6-0, 7-6 (7-5). He lost seven points in the first set.
Haas won 10-8 in the fifth set of a 2009 match at Wimbledon the only time he played Cilic in a tournament. Lopez is 3-1 versus Kohlschreiber.