Smashnova of Israel beat Castano in last year's finale.
Castano defeated Hungarian Kyra Nagy 6-3, 6-2, and eighth-seeded Smashnova beat Greek Eleni Daniilidou 6-1, 3-6, 6-3.
Four other seeds reached the second round as No. 2 Dutchwoman Michaella Krajicek beat France's Stephanie Foretz 6-1, 5-7, 6-1; No. 4 Czech Iveta Benesova beat countrywoman Katerina Bohmova 7-6 (12-10), 2-6, 6-4; No. 5 Spaniard Lourdes Dominguez Lino beat Russian Ekaterina Bychkova 6-4, 6-4; and No. 7 Martina Sucha defeated fellow Slovakian Jarmila Gajdosova 7-6 (7-5), 6-2.
In an upset, Czech Eva Birnerova knocked out third-seeded Czech Klara Koukalova 6-1, 3-6, 6-1.
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