British number one Heather Watson recovered to beat Russia's Evgeniya Rodina 3-6 6-1 7-5 in a gruelling first-round match at the Miami Open.
In hot and humid conditions, the 22-year-old world number 41 went behind to the 26-year-old, ranked 96, who had won both their previous matches.
Having levelled, Watson saw a 5-2 lead in the decider disappear before finally winning in two hours and 23 minutes.
She will play 13th seed Angelique Kerber of Germany in round two.
Watson, who lost in three sets to Kerber at Wimbledon last year, was 4-0 down within 15 minutes against Rodina, committing 20 unforced errors in the opening set.
But she prevailed after showing impressive determination in some energy-sapping rallies.
"I think both of us were feeling the same, it was just who could stick it out mentally and fight through the conditions," she said.
Regarding Kerber, Watson added: "We had a close match at Wimbledon, she's a very consistent, tough competitor so I will definitely have to up my game."
British wildcard Kyle Edmund was beaten by qualifier Robin Haase in the men's singles.
The 20-year-old British number three lost 6-2 6-2 to the world number 98 from the Netherlands.