How much further Heather Watson can go in the women's singles event at the Australian Open is very much up for debate with a niggling elbow injury and cramp hampering her performance here in Melbourne on the first day of competition.

However, the British women's No.1 is no soft touch and despite serving "at about 50% at first" and having treatment for dizziness, Watson still managed to make it through to the second round, defeating Alexandra Cadantu, of Romania 2-6, 6-3, 6-2.

The world No.50 said she planned to see a doctor before her second-round match with Ksenia Pervak, of Kazakhstan, tomorrow but the one thing that can be guaranteed about Watson is that she will give absolutely everything she has.

"Last time I played her was in the Australian Open juniors at the quarter-finals," Watson said. "I lost. She won [the title] that year. But I've seen her around. She's a lefty, a tough player, she makes a lot of balls."

On the surface, Watson is happy-go-lucky, always quick with a smile and genuinely nice but there is also a real steel about the 20-year-old that often gets overlooked and she was more annoyed with her performance than pleased with the recovery.

"I'm not really proud of it," she said. "At the beginning I definitely wasn't there. I wasn't playing well. I didn't have much energy. I don't know what it was.

"When I started cramping, I had to start hitting the ball [harder] because I couldn't move. I'm kind of thankful that I did cramp today, otherwise I don't know how the match would have ended up."

Trailing by a set and 3-2 and making an unusually high number of mistakes, Watson called the doctor, who took her temperature.

At the same time, Cadantu needed two injury time-outs and the extra time to recover was crucial for Watson as she roared back to victory.

"I was worried because I wasn't playing well, at all," a candid Watson admitted. "I thought it was a great opportunity, not being drawn against a top-five player in the world. I really wanted to take advantage. I had a great finish to last year and this is the first grand slam event of the year, so I was really looking forward to it, very motivated.

"She actually had two time-outs, so during that time I just ate two bananas, some gels, drank loads. I think having that little sit down, I got a little recharged and motivated."

Last October, Watson became the first British woman to win a WTA Tour title since 1988 when she won in Japan and the confidence she derived from that has helped her reassess her aims for 2013, with a place in the top 30 her next goal. "I feel a lot more confident and I believe in myself," she added. "Like this match, I felt I should have won and if I didn't I would have been extremely disappointed.

"I'm using it to push myself more in my training, make sure I'm working hard every day and not having a slack day."

Laura Robson, just three places behind her in the rankings, was due to play the American Melanie Oudin in the early hours of this morning.