Heading into today’s clash, Sun had a 1-8 singles record in 2025, struggling to find the form that saw her rise up the ranks last season.
Sun will face 31st seed Linda Noskova in the second round after the Czech was handed a first-round bye.
Sun and Noskova played against each other twice last year, with Sun defeating Noskova in the first round in Cincinnati, but Noskova triumphed when they played each other in the final in Monterrey.
Reaching the second round will earn Sun at least US$37,650 ($65,712) with the tournament champion taking home more than $2.09m.
Sun, who switched allegiance from Switzerland to New Zealand last year, burst on the international scene with a stunning quarter-final run at Wimbledon in June.
Less than two years ago Sun was 270th in the world and entered the qualifying stages at the grand slam in London as world number 123.
Her performance at Wimbledon saw her jump into the top 55 in the world. She moved into a career-high 39th in September, after making the final in Monterrey, Mexico. Her ranking hasn’t really taken a hit, sitting 49th heading into Indian Wells.