Serena Williams booked a place in the quarter-finals of the US Open on Monday with a hard-fought, three-set win over 15th seed Maria Sakkari. Williams required 2hr 28min to defeat the 25-year-old Greek player 6-3, 6-7 (6/8), 6-3 inside an empty Arthur Ashe Stadium at Flushing Meadows. “I just was fighting. She was doing so well, she was being so aggressive and I knew that I needed to do the same thing,” said Williams. The match swung in different directions, with Williams saving three break points in game five of the first set before breaking Sakkari to power to a first-set win. Inset two, Sakkari took a 4-0 lead in the tie-break before Williams hauled it back to 6-6. And in the deciding set, Williams had to break Sakkari’s serve twice to come back from 2-0 down. Little separated the two p...