Tennis: Serena Williams makes u-turn after walk-out mix-up with Simona Halep

Serena Williams made her way out to the Australian Open's main court during pre-match introductions, the voice booming over the stadium's speakers implored spectators to welcome "The world's number one player - from Romania, Simona Halep." Oops. Williams, wearing headphones, quickly pivoted and retreated back into the tunnel she'd just emerged from, making way for her fourth-round opponent on Monday. A couple of hours later, Williams wrapped up her 6-1, 4-6, 6-4 victory over Halep in a contest filled with momentum swings and a fantastic play by both. With this victory, the American stayed on course for a 24th Grand Slam singles title.