MELBOURNE, Australia - Two matches, two comebacks.

After rallying from a set and a break deficit in her first match against Kaia Kanepi, World No.1 Simona Halep kept her Australian Open campaign alive in dramatic fashion once more in the second round, defeating rising American Sofia Kenin, 6-3, 6-7(5), 6-4.

From 6-3, 3-0 in front, Halep held off a determined effort from the 20-year-old, the youngest player in the Top 50 and recent champion at the Hobart International, and needed to rally form a break down in the decider.

"I have no idea how I won this tonight. It's so tough to explain, " Halep said on-court immediately after the match.

"She's an amazing player and it was really difficult to stay there for every ball and run so much. I just fought, because I wanted to win."

After earning just her second break of serve in the match overall, Kenin moved two games away from the biggest victory of her career to date, and was two points from a 5-2 lead.

Nonetheless, Halep bounced back and wrestled control away from the rising American, raising her level to set a third round clash against Venus Williams.

The World No.1 had the perfect start to the second-round encounter, as she bookended the first set with breaks of serve in the first and last games. 

On serve, she lost just six points in four service games and was never taken to deuce, as she hit nine winners to just seven unforced errors and took advantage of 12 miscues from Kenin's racquet.

A mini-battle in the fourth game in the second set helped Kenin navigate her way back into the match, as she got on the board after four deuces and broke to love to win her first Halep service game of the match.

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The 20-year-old stayed in touch from there, holding serve with ease to keep pace all the way through to a tiebreak, before winning four of the last five points of the ensuing tiebreak to push Halep the distance.

"I think I fought, and I fought hard, and that's why I could win tonight. It was a very tough one. She's very solid. Was really tough to make some winners, some points, easier," Halep said.

"I think the level was very high. I missed some balls. I couldn't play the same at the 3-0, 4-0 game, that I lost that game. I went a little bit down with the confidence, but in the end, I won. It's all that matters."