Top seed Serena Williams and Caroline Wozniacki ensured the Auckland Classic retained its two main drawcards as they battled to second-round victories on Thursday, though promising teenager Coco Gauff was knocked out. Williams needed two hours to outlast fellow American Christina McHale with a 3-6 6-2 6-3 victory, while Wozniacki, who is playing her penultimate tournament, fought back to overcome a tenacious Lauren Davis 6-1 4-6 6-4. Gauff, however, was upset by Germany’s Laura Siegemund 5-7 6-2 6-3 in a 2hr 14 min match that opened Thursday’s action on the main...