Heather Watson overcame some poor serving to move into the second round of the Abierto Mexicano in Acapulco.
The British No 2 served 10 double faults but was still able to beat qualifier Bethanie Mattek-Sands in straight sets 7-5 6-3.
Watson was able to battle through those lost points and broke the American, more known as a doubles player, on six occasions.
She will face second seed Kristina Mladenovic in the second round after the Frenchwoman eased to a 6-2 6-3 win over Varvara Lepchenko.
The two other seeds in action on Monday also progressed.
Seventh seed Lesia Tsurenko had little trouble in defeating France's Chloe Paquet 6-2 6-1 while Andrea Petkovic, seeded eight, needed three sets to beat Jamie Loeb 2-6 6-1 6-3.
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