The third-seeded Ormaechea got off to a bit of a slow start against qualifier Nicole Gibbs, going down 2-0 in the first set, but from there she reeled off 11 straight games en route to a 62 61 triumph.
Though this was Ormaechea's first main draw win at a WTA-level event since last year's US Open, she did win both of her singles matches in Argentina's Fed Cup victory over Japan earlier this month.
Burnett went up 4-1 and two breaks before a rain delay forced the players off the court and thwarted her momentum. Upon resumption, she surrendered four straight games and then had to fight off four set points down 5-4. That was the first of seven straight games the Italian won en route to a 75 64 defeat of Torró-Flor, who is ranked almost 100 spots higher than Burnett.
"At the beginning I was playing really well, very aggressive," Burnett said. "It was a pity at 4-1 that it started to rain and I lost my momentum and she got back in the match. It was tougher than I'd like but I'm happy that I got the win and I feel every day I'm playing better."
Burnett commented on playing her first clay court event of the season.
"I have been playing on hardcourts for a long time now," Burnett said. "Fed Cup was indoors on very fast courts. It's not easy to get used to this. Practicing points before the tournament, I wasn't happy, but fortunately during the match I got used to it and it got better."