Squinting into sun glare, Karin Knapp caught several tosses and tried relocating her release to a spot where she could see the ball clearly. No matter how much she shifted sight lines, the 49th-ranked Italian couldn’t escape her serve struggles — or Taylor Townsend’s brand of heat stroke.

The 17-year-old American delivered a biting serve to set up her blistering forehand—and saved all six break points she faced in the second set—scoring the biggest win of her young career, 7-6 (1), 6-1, to reach the Indian Wells second round. Knapp defeated Americans Christina McHale and Alison Riske in succession to lead Italy to a 3-1 Fed Cup victory over the host United States last month.  Townsend, touted as one of the most gifted young Americans, may have caught a glimpse of those matches as she came out hitting her sweeping lefty forehand to Knapp’s weaker two-handed backhand wing to draw the short ball.

The world No. 337 broke to open then backed up the break with a love hold. Knapp responded with a love hold before breaking back for 2-all. At that point Townsend’s baby blue Nike visor looked completely saturated with sweat and the expanding pool of empty plastic water bottles scattered beneath her court-side seat suggested the role the sun would play. Though Knapp is nine years Townsend’s senior and has played 400-plus more matches, she didn’t cope with the conditions as well as the teenager. They traded breaks in the seventh and eight games before Townsend hit her cross court forehand to draw another backhand error and break for 5-4. Nerves restricted her left arm as she dumped two of her six double faults when serving for the set; Knapp swooped in for a slick forehand volley to break for 5-all.

The tiebreaker was all Townsend. Her ability to hold the ball on her forehand creates deception that caused confusion for Knapp, who had trouble reading the direction of that shot and contributed to her own demise clanking four consecutive errors to fall behind 5-1 in the breaker. Attacking net, Townsend forced an errant backhand to earn five set points and closed when Knapp, who declined to wear a cap or visor to try to combat the sun, coughed up her seventh double fault to drop a 56-minute opening set that saw the pair combine for 53 unforced errors.

Though she played patches of hit-and-miss tennis and her ambition can get the best of her, when Townsend finds the sweet spot she can sting the ball with vigor. The wild card staved off two break points crunching a pair of service winners to hold for a 1-0 second-set lead. Townsend is still raw — if she can get fitter it should help refine her shot selection, enabling her to play higher-percentage tennis and she must sharpen the second serve — but she’s a clean ball striker and bold shot-maker, who can hit creative forehand combinations and exhibits soft feel in the frontcourt. Staring down another break point in the third game, Townsend opened the court with a slice serve wide then whipped a forehand winner off the opposite sideline before scarring Knapp with a slashing ace wide to hold for 2-1.

Flipping through pages of her noteback during changeovers, Townsend produced a diary-worthy game, tomahawking a forehand winner down the line and burying a body serve into the hip to hold at love for 4-1. Defending her second serve more effectively — the teenager won 50 percent of her second-serve points (15 of 30), while Knapp won just 33 percent (8 of 24) of her second deliveries — Townsend converted five of six break-point chances and denied three break points in serving out the 94-minute victory. She punctuated it by waving her index finger (painted pumpkin orange) toward supporters and wearing a wide smile. She'll face another Italian, 2013 U.S. Open semifinalist Flavia Pennetta, in the second round.