What's happening in sport? Five things to know

Updated 10:29 AM ET, Thu January 25, 2018

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(CNN)It started with a sideswipe and ended with a direct message.

Serena Williams has taken to Twitter to confront US tennis player Tennys Sandgren demanding that he make an "apology" following media scrutiny of his Twitter account which suggests he is sympathetic to alt-right views -- a charge he denies.
Early on Wednesday, Williams had tweeted "turns channel" when TV coverage of Sandgren's quarterfinal match was about to start.
Williams then returned to Twitter later in the day to address Sandgren directly.
"@TennysSandgren I don't need or want one. But there is a entire group of people that deserves an apology," Williams wrote. "I cant look at my daughter and tell her I sat back and was quiet. No! she will know how to stand up for herself and others -- through my example."
Below the tweet this message was added: "Maturity is being able to apologize and admit when you're wrong because you know that your mistakes don't define you."
    Earlier in the the week Sandgren hit back at media scrutiny of his tweets claiming that the coverage was "sensationalist."
    However, screengrabs of some of the tweets he had deleted earlier in the week revealed that he had made derogatory comments about blacks, Muslims and homosexuals -- in 2012 he wrote: "stumbled into a gay club last night. .. my eyes are still bleeding."
    He has subsequently apologized.
    "In regards to the gay club tweet from 2012, I used poor and harsh words to describe a bad experience, and is not indicative of how I feel about the people in that community," Sandgren wrote. "To everyone I offended with that, pls accept my apology."
    Sandgren's best run at a major tournament ended Wednesday with defeat to South Korea's Hyeon Chung.

    Final showdown

    Both Simona Halep and Caroline Wozniacki know what it's like to lose grand slam finals but on Saturday one of them is guaranteed to taste victory for the first time.
    World No. 1 Halep -- a finalist at Roland Garros in 2014 and 2017 -- saved two match points against Angelique Kerber before dispatching the German 6-3 4-6 9-7 in front of a packed crowd at the Rod Laver Arena.
    Wozniacki, meanwhile, made lighter work of her semi, beating Elise Mertens 6-3 7-6 to reach her first grand slam final in four years.
      "I'm just excited -- it's another finals," Wozniacki said. "Regardless of what happens now, I've done my best. When you go out there on Saturday, you have everything to win."
      In the men's draw, Kyle Edmund's sensational run has come to an end.
      The Briton, who has been flying the flag for Britain in the absence of Andy Murray, was soundly beaten by Marin Cilic in straight sets 6-2 7-6 6-2.
      Edmund exits with his reputation massively enhanced, and a tidy check worth around $700,000.
      Cilic's opponent will be either Roger Federer or Hyeon Chung who play Friday.

      Thawing of relations?

      North Korea's women's ice-hockey team has arrived in South Korea ahead of next month's Winter Olympics.
        The players were greeted by their South Korean counterparts, exchanging flowers after arriving on a bus which crossed the border via the demilitarised zone on Thursday.
        The unified Korean team are set to start training together for the first time at the Jincheon National Training Center.
        There is no time to waste. Their first match as a unified team is scheduled to take place on February 10. Their opponents are those bastions of neutrality, Switzerland.

        Tiger's career back on course

        We'll know a bit more about Tiger Woods' fitness by the end of Thursday.
        Woods, 42, is competing in the Farmers Insurance Open at Torrey Pines -- his first tournament of 2018 and only his second in almost a year following a layoff to recuperate from another back operation.
        The 14-time major champion was in good spirits ahead of the first round, saying his life is "infinitely better" than 12 months ago.
          "It's all finished now, (my back's) fused and my quality of life is infinitely better than it was at this point last year," Woods told a pre-tournament news conference. "My expectations have tempered a little bit because I haven't played.
          "I just want to play on tour and get into the rhythm again. I'm going to grind it, give it everything I have. But I'm just trying to build toward April. I'm trying to play a full schedule and build for the Masters."

          Dune racing in Marrakech

          Slight change of pace ...
          Earlier this month, Nicki Shields joined Formula E racers Nelson Piquet Jr. and Mitch Evans for a race with a difference in Morocco.
          Before battling it out on track in the Marrakech ePrix, there was a chance to claiming bragging rights in a buggy race on the dunes outside the city.
          Round four of the Formula E 2017/18 championship takes place in Santiago on February 3.