Montanes, seeded first in Casablanca, lost one point in the tiebreaker and one game in the second set in beating No. 7-seeded Fabio Fognini, 7-6 (7-1), 6-1. Fognini had won more points than Montanes until the tiebreaker but, once that started, Montanes won 66 percent of the points the rest of the way.
He'll go against unseeded Pablo Andujar in Saturday's semifinals. Andujar breezed past Pere Riba 6-2, 6-2 by winning 70 percent of the points on serve even with dropping serve once.
Fifth-seeded Potito Starace ousted No. 3-seeded Gilles Simon 6-4, 3-6, 6-4 despite losing his serve four times. Starace had five breaks against Simon, with two coming in the third set.
Victor Hanescu, the No. 8-seed, capped the day's schedule with a 6-7 (1-7), 7-5, 6-2 win over Andrey Kuznetsov.
Montanes is 2-0 in his career against Andujar. Hanescu and Starace are 2-2 in their previous meetings.