Keys contemplates what it will take to reach the summit

Madison Keys is ranked in the top 10 in the world, a Grand Slam semifinalist who just played for an Olympic bronze medal and has earned prize money of well over $4 million in her short pro career.

She's also only 21, much closer in age to her high school days than to No 1 Serena Williams, and she's the youngest woman in the top 20 by nearly 18 months.

This is where the American finds herself as she heads into next week's US Open - an established pro with the skill set to win major titles, yet competing in a sport in which many players peak in their late 20s and even early 30s.