Actress Allison Janney took home her first Oscar in the Best Actress in a Supporting Role category for her powerful performance in "I, Tonya" at the 90th Academy Awards ceremony here.She won the trophy for her role as Tonya Harding's mother LaVona Golden in the biopic "I, Tonya"."I did it all by myself," she joked in her acceptance speech, then paused for a moment before saying "that's nothing farther from the truth".Her comment was met with a round of applause.The actress, who looked elegant and stylish in a red gown, went on to thank the whole team of the film and important people in her life.Janney, who exclaimed that she did not see this coming, thanked her fellow nominees and said: "You represent everything that is good and right and human.""Joanne Woodward, thank you for your encouragement and generosity that gave me the confidence to think I could pursue a career in acting. To my mother and father, Jay; my family; my family of friends; the staff. I love you," she added.She was in the race to win the coveted trophy with Mary J. Blige ("Mudbound"), Lesley Manville ("Phantom Thread"), Laurie Metcalfe ("Lady Bird") and Octavia Spencer ("The Shape of Water").The 90th award gala was held her at Dolby Theatre on Sunday night.