Serena holds off Halep to reach semis

World number one Serena Williams fended off spirited Simona Halep on Wednesday, downing the fifth-seeded Romanian 6-2, 4-6, 6-3 to reach the US Open semi-finals. Williams, seeking a record seventh US Open title and 23rd Grand Slam crown, fired 18 aces en route to the triumph, which set up a Thursday evening meeting with first-time Grand Slam semi-finalist Karolina Pliskova for a place in Saturday's championship match.