A tennis battle of the ages against Serena Williams will have to wait after rising star Coco Gauff was upset in the second round of the ASB Classic in Auckland.

The tournament’s dream scenario of an all-American quarter-final between 15-year-old Gauff and 38-year-old legend Williams was ruined when the youngster fell 5-7 6-2 6-3 to Germany’s Laura Siegemund on Thursday.

Gauff couldn’t handle another blustery Auckland day and the dogged consistency of her lower-ranked opponent, finishing the match with 49 unforced errors including seven double faults.

Despite the urging of the crowd and regular rev-ups between games from her father Corey, Gauff appeared rattled by her inability to find her timing.

The world No.67, who took the tennis world by storm when reaching the fourth round at Wimbledon in June, fought back from 5-3 down to claim the first set.

However, her game then deserted her in what will be her last singles match before making her Australian Open debut.

Because of her youth, Gauff must play a restricted number of tournaments so won’t appear in WTA events at Adelaide or Hobart next week.

Williams is up against compatriot Christina McHale in her second-round match.

The evening session was to stage matches involving fourth-seeded German and two-time defending champion Julia Georges, along with fifth-seeded Dane Caroline Wozniacki.