Naomi Osaka suffered a shock defeat to Karolína Muchová in the second round of the Madrid Open, but the world number two was still positive as she took to Twitter to thank her fans for supporting her.The Japanese star has struggled on clay throughout her career, having yet to win a title on the surface. Osaka’s recent loss further confirmed that her game is not ideally suited to playing on this type of court.It appeared at one stage like she’d wrestled back the initiative against Muchová. Down a set and a break, the 23-year-old fought valiantly to level the match and force a decider. Despite being on the front foot, though, Osaka comprehensively lost the final set 6-1 as the Czech capitalized on a number of uncharacteristic errors from her opponent.Speaking in her press conference afterwards, Osaka admitted that she’s still learning on this surface.“I’m not sure how others play, but I’m learning that on clay I can't afford to not swing through every ball, because that automatically takes me from offence to defence,” she said.“And maybe if I start being able to move better I can risk starting to play on defence, but as of right now I think I should be the aggressor.”While the loss will undoubtedly sting, the four-time Grand Slam winner also took to social media to share her optimism for the future.Addressing her defeat on Twitter, Osaka wrote: “Caught an L today but beyond happy with how hard I fought and very grateful for the team I have around me. I already know something good is coming for me so I’ll keep putting my head down and working hard. Tomorrow is a new day! Thank you guys for the support.”Next up for this year’s Australian Open winner is another Premier Five event –– the Italian Open. Clearly, the 23-year-old has a lot to work on and the prospect of winning the tournament appears slim, but if anyone can rise to the occasion, it’s Osaka.