Aug 27 (Reuters) - Bianca Andreescu scripted a U.S. Open fairytale in 2019 when she won the Grand Slam event as a teenager playing in the main draw for the first time. If the Canadian, now 21, were to repeat that script this year, it would be an even bigger shock. Injuries and a pandemic have combined to put the brakes on what some had predicted would be a meteoric rise to tennis super stardom. Between her victory over Serena Williams in the 2019 final and a return to Flushing Meadows this week, Andreescu has managed just one win at Grand Slam tournament - a first-round victory over Mihaela Buzarnescu at this year"s Australian Open. That was followed by first-round exits at both the French Open and Wimbledon. As dire as those results may sound, they were more upbeat than Andreescu"s 2020 Grand Slam campaign that was written off by injury and sickness that included everything from tearing the meniscus in her left knee to testing positive for COVID-19. The run-up to the U.S. Open - a second-round loss in Montreal and first-round exit in Cincinnati - offered few hints of a long stay in Flushing Meadows but Andreescu assures that progress is being made as she focuses on the long term. "I got goosebumps when I walked onto Armstrong the first day," Andreescu told reporters in New York, referring to the court at Louis Armstrong Stadium at Flushing Meadows. "It just brought me back to 2019." Andreescu added, "But I"m not the same person back then than what I am now. Taking so much time off, I feel like it helped me in many ways. But then getting into that competitive mindset, it kind of brought me back a little bit. I feel like that"s also a reason why I haven"t had the results I wanted." Andreescu returns to the U.S. Open with a new attitude and a new coach in Sven Groeneveld, a former professional player, who has worked with past Grand Slam champions Monica Seles and Maria Sharapova. The pair started officially working together this month. Andreescu said she is already seeing a difference on the court. "Right now I"m basically applying what he"s been telling me," Andreescu said. "I see a huge difference in practice. That whole confidence thing, I"m just going to have to play matches. That"s all I can really say, play matches, continue to train hard, prepare well, prepare mentally." Andreescu added, "I know I"m going to get back to or get to where I want to be."