Garbine Muguruza's remarkable return to form moved up another level on Thursday after defeating fourth seed Simona Halep to set up an Australian Open final showdown with American Sofia Kenin. The unseeded Spaniard, a two-time Grand Slam champion, reached her first Melbourne final with a tough 7-6, 7-5 victory at a hot and humid Rod Laver Arena, fighting back from behind in both sets. Muguruza, who suffered a calamitous drop in form last season, is the first unseeded player to reach the women's final since Belgium's Justine Henin in 2010. "Very excited to be in the final, it's a long way to go and I have one more match on Saturday," said Muguruza, the former world No 1 who is now ranked 32. "I wasn't thinking that I was down, I was thinking keep going and at some stage you're going to have an opportunity. "Luckily I have 48 hours now to recover and get ready for the last match. We train all of our career to be able to play on this court and in [front of] this crowd." Halep and Muguruza, who have both won the French Open and Wimbledon, were too close to split in a nervy first set. In sweltering heat, with play on the outside courts suspended earlier as temperatures hit 38° Celsius, they grappled all the way to the tie-breaker. Muguruza squandered two set points in the breaker while saving two more for Halep, and then clinched it with a stop volley that Halep couldn't get back over the net. It was the first set Halep had dropped all week and she reacted by mangling her racquet and slumped in her chair, shaking her head. The 28-year-old recovered her poise and broke Muguruza for a 3-2 lead in the second set, before Muguruza broke back and then held to make it 6-5. Halep, so serene in Melbourne up until now, cracked as she served to stay in the tournament, saving the first match point but then netting a backhand as Muguruza surged forward on the second. Kenin, the American 14th seed, earlier stunned world No 1 and home hope Ashleigh Barty 7-6, 7-5 to reach her first Grand Slam final. Kenin looked shell-shocked in the immediate aftermath of her surprise defeat of home hope Barty, saying: "She's such a tough player, she's playing really amazing. I knew I had to really find a way to win. "I'm just speechless, I honestly can't believe this. I've dreamed about this moment since I was five years old." "I've worked so hard to get here. I really had to fight out here. There's a reason she's No 1."