Aryna Sabalenka's early exit at the Dubai Tennis Championships has left tennis fans shocked.Sabalenka got her campaign at the WTA 1000 event underway on Tuesday (February 20), with a second-round clash against Donna Vekic. The second seed started the game on the front foot, winning the first set to take a lead in the contest.Vekic, however, fought back against the Belarusian, who was playing for the first time since she successfully defended her Australian Open title last month. The Croatian hit 14 aces and won 12 of the last 13 games of the match to beat Sabalenka 6-7(5), 6-3, 6-0 in two hours and 22 minutes.Fans were left shocked and amused by Sabalenka's defeat in Dubai, with one stating that this would continue Iga Swiatek's reign atop the WTA rankings."Jesus Christ we’re never getting rid of Swiatek as world number 1 are we?" said one fan on X (formerly Twitter).Another fan was not impressed with Sabalenka for the bagel in the deciding set."Sabalenka when you said you wanted to get closer to Iga as far as bagels go this is not what I thought you meant girl...." The fan wrote.Here are some more fan reactions:"In tennis, I swear it's not over until it's over" - Donna Vekic on her comeback win against Aryna SabalenkaDonna Vekic defeated Aryna Sabalenka at the 2024 Dubai Tennis Championships.Aryna Sabalenka might be one of the strongest players on the women's tour currently, but Donna Vekic holds the upper hand in the head-to-head record with the World No. 2.The two players have met eight times to date, with Vekic winning six times. They first met in the Saint Petersburg semifinals in 2016, where the Croatian won in three sets. Most recently, the two players locked horns in the quarterfinals of the 2023 Australian Open, which Sabalenka won on the way to lifting her maiden Grand Slam title.Speaking after her win at the 2024 Dubai Tennis Championships, Vekic acknowledged her strong record against Sabalenka but admitted that the defeat in Melbourne last year stung a bit."I know that I have a winning head-to-head [against Aryna Sabalenka]. But she beat me in Australia last year in the quarterfinals. That one hurt quite a bit," she said.In Dubai, Vekic came from a set and a break down to beat the World No. 2. She stated that momentum in tennis matches can turn very quickly and that she wasn't thinking about the score during the match but was focused on playing each game as if it were her last one."In tennis, I swear it's not over until it's over. Like I said, matches can turn around with one point. To be honest, I wasn't really thinking... These big leads don't mean nothing anymore. You just focus and play each game as if it's the last," she added.Vekic will next face Sorana Cirstea, who defeated Veronika Kudermetova 6-1, 6-4.