British number one Heather Watson battled through illness to produce a stirring comeback and edge Alexandra Cadantu in the Australian Open first round.

Cadantu started brightly and had the Brit on the backfoot from the outset, forcing Watson to defend against break point in her first service game.

The 20-year-old fought the Romainian off, but could not hold her back for much longer and lost serve to fall 2-1 behind.

Watson made an instant reply to level the score at 2-2, but errors started to creep into her game allowing Cadantu to race to a 6-2 triumph.

A medical timeout was called midway through the second set, with Watson having her temperature and blood pressure checked in the searing Melbourne heat.

Cadantu struggled to cope when play resumed as Watson recovered to claim four games in a row and level the match at a set apiece.

The Romanian appeared to suffer a leg injury in the decider but Watson showed no mercy, claiming an early break before following up to take the match 2-6 6-3 6-2.