Former US Open winner Bianca Andreescu has been out of action since last August due to a stress fracture in her back. That, however, didn't stop the Canadian from tuning into Rafael Nadal and Jordan Thompson's marathon match in Brisbane on Friday (January 5).Nadal kicked off his quarterfinal encounter against the Australian on a good note as he took the opening set 7-5. The Spaniard, however, began to tire soon and received medical treatment for pain in his left hip muscles during the second set.The 37-year-old eventually came up with his first match point at 5-4 up, which was saved by some gutsy serving from Thompson. The 22-time Major winner again held two match points in the second-set tiebreaker. He failed to convert them though, allowing the local favorite to push the match to a decider.Rafael Nadal was visibly exhausted from the grind of the match by then, surrendering the match 7-5, 6-7(6), 3-6 to Thompson. Bianca Andreescu, on her part, took to social media to express her shock at the match lasting as long as it did.She also admitted that she hadn't watched a tennis match in quite some time before waxing philosophical about the challenges of the sport."Started watching tennis again today for the first time in a long time and what’s on is Thompson vs Nadal… lol. 2 hours 40 minutes and the third set just started. This sport is something else," Bianca Andreescu wrote on her X (formerly Twitter) handle.Bianca Andreescu has been unfortunate with injuries since US Open 2019 triumphBianca Andreescu, meanwhile, has had regular run-ins with injuries since her breakout season in 2019. The Canadian won her maiden Major title in New York against all odds before hitting a rough patch in the following years.Andreescu was on the sidelines in 2020 due to a knee injury. And while she did return at the 2021 Australian Open, she again missed a few weeks of the WTA Tour after testing positive for COVID-19 in April that year.The Canadian played every big tournament from May till November before unfortunately contracting COVID-19 again towards the end of the year. She was subsequently forced to sit out of the 2022 Australian Open and the two WTA 1000 tournaments in Indian Wells and Miami due to complications from the virus.Bianca Andreescu injured her ankle during her fourth-round match against Ekaterina AlexandrovaBianca Andreescu then had a relatively untroubled time on the pro tour until this year. The 23-year-old had to be wheeled out of the court after she suffered a horrible ankle injury against Ekaterina Alexandrova in Miami.Andreescu's luck ran out on her again during the North American hardcourt swing as she picked up a back injury. The former US Open winner hasn't played since then. She also admitted recently that she will not play at this year's Australian Open."No, sadly I won’t be at the Australian Open," Andreescu said during Canada's Olympic Committee summit in Paris (via Sportstar). "Right now I’m looking at (returning) after the Australia Open or the American Tour, so Indian Wells... maybe."