The Swedish world number eight has not dropped a set all week on the Catalan clay and will play unseeded Thiemo de Bakker for a place in Sunday's final. Dutchman De Bakker, a former junior world number one, took his first top-10 scalp when he upset third-seeded Frenchman Jo-Wilfried Tsonga 6-4, 3-6, 6-3 in a match briefly interrupted by rain.
The 21-year-old ignored the partisan support from local fans for the flamboyant Tsonga and sealed victory when the erratic world number 10 went long with a forehand return.
Second seed Soderling saved the only break point he faced against 59th-ranked Schwank, converting three of his four chances, and said he felt his form on the red dust was even better this year than last.
Spanish players continued their impressive performance on clay this year when Fernando Verdasco and David Ferrer advanced to the last four.
Fifth seed Verdasco edged out Ernests Gulbis of Latvia 6-2, 7-6 and will play Ferrer on Saturday after the eighth seed thumped Brazilian Thomaz Bellucci 6-4, 6-0.
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