Coco Gauff extended her unbeaten start to the year on Wednesday but had to survive a second-set wobble in a 6-3, 7-5 win over Jodie Burrage at the Australian Open.Big-hitting Burrage served for the second set at 5-3 but nerves overcame her in a maiden appearance on Rod Laver Arena and she double-faulted twice to allow Gauff to level.