Heather Watson digs deep to defeat Alexandra Cadantu

Watson’s prospects looked bleak as she struggled to come to terms with Cadantu, who made few errors in the opening half of the match.

Guernsey native Watson was in dire straits at a break down in the second set and worse appeared yet to come when she called for a trainer as she battled a bout of cramp.

She was treated by a doctor, with the break in play appearing to rejuvenate her as she overturned the deficit to set up a second round meeting with Ksenia Pervak of Kazakhstan, who beat Germany’s 32nd seed Mona Barthel.

“At the beginning I definitely wasn’t there,” Watson admitted afterwards. “I wasn’t playing well. I didn’t have much energy today. I don’t know what it was. I think I’m going to see the doctor.”

On a day of few shocks, Novak Djokovic, Maria Sharapova and Venus Williams all overcame first-round opponents with straight-sets victories.

Defending men’s singles champion Djokovic made short work of Paul-Henri Mathieu of France, prevailing 6-2 6-4 7-5 as he bids to become the first man in the Open era to win three successive titles in Melbourne. The Serbian faces Ryan Harrison of the United States next.

Sharapova, last year’s beaten finalist in the women’s singles, made a ruthless start to her championship, seeing off fellow Russian Olga Puchkova 6-0 6-0.

“It’s tough to feel completely satisfied,” Sharapova said. “You always want to improve on things and work on certain things that you feel will help you in the later rounds towards the end of the second week. But overall I was happy with the way I started considering I didn’t play any matches coming in.”

Williams edged closer to a potential third-round battle with Sharapova by beating Galina Voskoboeva of Kazakhstan 6-1 6-0.

“A win is a win no matter what it is, but it’s nice when it’s more routine,” said Venus, whose sister Serena plays her first-round match today against Edina Gallovits-Hall of Romania.

Elsewhere Ana Ivanovic of Serbia beat Hungary’s Melinda Czink 6-2 6-1, China’s Li Na beat Sesil Karatantcheva of Kazahkstan 6-1 6-3 and Polish fourth seed Agnieszka Radwanska saw off the challenge of Aussie wildcard Bojana Bobusic, 7-5 6-0.

Home favourite Lleyton Hewitt, playing a record 17th consecutive Australian Open, bowed out at the first hurdle 6-7 5-7 3-6 to eighth seed Janko Tipsarevic of Serbia.

The duo slugged it out for three hours in a high-quality match. Hewitt, who was unseeded, said: “Against quality players, you’ve got to take your chances, but to his credit Janko raised his level and played some great points.”

British trio Andy Murray, Jamie Baker and Laura Robson are all due to play first-round matches tonight or in the early hours of Tuesday morning, GMT.

Murray was due to begin his first grand slam since winning the US Open against Dutchman Robin Haase, while Baker, who came through three qualifying rounds to reach the main draw, was scheduled to face Lukas Rosol of the Czech Republic at approximately 4am on Tuesday morning.

Britain’s Robson, who was born in Melbourne, was due to take on Melanie Oudin of the United States at a similar time.

Victoria Azarenka begins the defence of her title against Monica Niculescu in the second match on Rod Laver Arena, before four-time champion Roger Federer takes on Frenchman Benoit Paire.