Sport - Sport (UK) Huddersfield Town appoint Jan Siewert from Borussia Dortmund as new manager 2019-01-21T17:39:35.000000000+00:00 Huddersfield appoint Jan Siewert to succeed David Wagner as the club's manager on a deal until 2021. Australian Open: Serena Williams retreats after walkout mix-up 2019-01-21T17:29:26.000000000+00:00 Serena Williams is forced to turn back as she walks on to court while her opponent, Simona Halep, is being announced to the crowd before their fourth-round match at the Australian Open. Serena Williams knocks out Simona Halep in epic Australian Open clash - highlights 2019-01-21T17:29:18.000000000+00:00 Serena Williams outlines why she is the favourite to win the Australian Open with a 6-1 4-6 6-4 win over world number one Simona Halep in a high-quality last-16 match. Wolves boss Nuno Espirito Santo charged for celebration in 4-3 win over Leicester 2019-01-21T17:15:41.000000000+00:00 Wolves boss Nuno Espirito Santo is charged with misconduct after running on to the pitch to celebrate his side's winner against Leicester. Ashley Cole: Derby County sign veteran ex-England defender 2019-01-21T17:01:34.000000000+00:00 Derby County sign former England, Chelsea and Arsenal left-back Ashley Cole on a deal until the end of the season. Serena Guthrie column: Five things the Quad Series taught us for the World Cup 2019-01-21T16:09:24.000000000+00:00 In her column for BBC Sport, Serena Guthrie explains what England learned from the Quad Series as they prepare for the World Cup. Australian Open: Novak Djokovic confident over fitness after beating Daniil Medvedev 2019-01-21T15:30:01.000000000+00:00 Novak Djokovic is confident he will be ready to face Kei Nishikori in the Australian Open quarter-finals after a gruelling last-16 battle against Daniil Medvedev. Three Sodje brothers jailed for taking charity money 2019-01-21T15:24:07.000000000+00:00 The ex-footballers and former rugby player siphoned off money meant to help poor African children. Australian Open: Kei Nishikori through after five-set win over Pablo Carreno Busta 2019-01-21T15:19:32.000000000+00:00 Kei Nishikori produces another sensational comeback to reach the Australian Open quarter-finals with a five-set win over Pablo Carreno Busta. Serena Williams knocks out Simona Halep in epic Australian Open clash 2019-01-21T14:38:15.000000000+00:00 Serena Williams impresses in a high-quality 6-1 4-6 6-4 last-16 win over top seed Simona Halep at the Australian Open.