World number one Simona Halep survived a scare to beat American Sofia Kenin and reach the Australian Open third round.

The Romanian had been cruising to victory after leading by a set and a break before finding herself a break down in the third.

She kept her composure to break back in the seventh game of the decider before going on to win 6-3 6-7 (5-7) 6-4.

"I have no idea how I won," said Halep, who next faces Venus Williams.