The 43-year-old Date-Krumm is 23 years older than Puig and first played here in 1989 in her WTA grass court debut, making the quarterfinals. She previously faced off with Puerto Rican No.1 Puig in the Monterrey quarterfinals earlier this year and pulled out a tight three-setter.
This one was even closer, with Date-Krumm having three match points in the third set tie-break at 6-3, but she lost four points in a row before fighting off a match point for Puig and eventually sealing a 2-6, 6-4, 7-6(7) triumph.
Two more singles upsets saw lucky loser Timea Babos score a 6-2, 6-1 victory over No.11 seed Madison Keys and Petra Cetkovska record her first win in four meetings with No.8 seed and 2009 Birmingham champion Magdalena Rybarikova, 6-4, 7-5.
Others moving on included second-seeded Samantha Stosur, third-seeded Sloane Stephens, fourth-seeded Kirsten Flipkens, sixth-seeded Klara Koukalova, ninth-seeded Zhang Shuai and 15th-seeded Alison Riske.