Britain's Francesca Jones said she had "no idea what just happened" after fighting through injury to reach the Auckland Classic quarter-finals.
Jones registered the biggest win of her career on Monday with a three-set victory over world number 15 Emma Navarro.
It looked as though the 25-year-old was feeling the after-effects when she went a set and a break down against Austrian qualifier Sinja Kraus, having twice called for the physiotherapist.
However, she regrouped and lost just two further games in a 1-6 6-4 6-1 victory.
"I'm actually really relieved that's over," Jones told Sky Sport in New Zealand.