Tsitsipas becomes first Greek to reach major semifinal

   It's hard to say what's most impressive about Stefanos Tsitsipas.
   His powerful serve? His flowing one-handed backhand? His poise? His soulfulness?
   The 20-year-old phenom avoided a letdown after ousting Roger Federer, beating 22nd-seeded Roberto Bautista Agut of Spain 7-5, 4-6, 6-4, 7-6 (2) today to reach the Australian Open semifinals in Melbourne.
   "I'm just living the dream, living what I've been working hard for," Tsitsipas, seeded 14th, said in an on-court interview. "I feel a bit emotional but not too much because I really worked hard to get here, the semis of a Grand Slam."
   Tsitsipas blasted 22 aces and won 84 percent of the points on his first serve (62 of 74). He became the first Greek and youngest man since Novak Djokovic in the 2007 U.S. Open to reach a Grand Slam semifinal.
   Tsitsipas will face second-seeded Rafael Nadal, who dismantled unseeded Frances Tiafoe 6-3, 6-4, 6-2. Tiafoe, who turned 21 on Sunday, won the $100,000 Stockton Challenger in 2016 at age 18.
   Danielle Collins also backed up a big upset to reach her first major semifinal. In a matchup of unseeded players, the 25-year-old American defeated Anastasia Pavlyuchenkova of Russia 2-6, 7-5, 6-1.
   Collins was coming off a 6-0, 6-2 victory over second-seeded Angelique Kerber, who won the first of her three Grand Slam singles titles in the 2016 Australian Open.
   Pavlyuchenkova played for the Sacramento Capitals of World TeamTennis in 2006 at age 15.
   Collins will play eighth-seeded Petra Kvitova, who eliminated 15th-seeded Ashleigh Barty of Australia 6-1, 6-4 to reach her first major semifinal since winning her second Wimbledon title in 2014. Kvitova suffered career-threatening cuts to her left (playing) hand in a knife attack at her home in the Czech Republic in December 2016.
   Kvitova's victory ensures that Simona Halep will be deposed as the world No. 1, wtatennis.com reported. Either Kvitova, Naomi Osaka, Elina Svitolina or Karolina Pliskova will replace Halep. Only Pliskova has been ranked No. 1.
   In the women's doubles quarters, second seeds and defending champions Timea Babos of Hungary and Kristina Mladenovic of France beat ninth-seeded Raquel Atawo (Cal, 2001-04) of Sacramento and Katarina Srebotnik of Slovenia 6-4, 7-5.