|Venue: Melbourne Park Dates: 18-31 January|
|Coverage: Live radio and text commentary on all Andy Murray matches. Listen to Tennis Breakfast on Radio 5 live sports extra and the BBC Sport website from 07:00 GMT every day.|
Britain's Heather Watson and Kyle Edmund both suffered first-round exits on day one at the Australian Open.
Watson, ranked 79th in the world, failed with a chance to serve for a straight-set win over Hungary's Timea Babos before losing 6-7 (4-7) 7-5 7-5.
Babos, ranked 60th, played with aggression and power to claim victory in just under three hours.
Edmund was hampered by cramp as he lost 1-6 7-6 (7-4) 4-6 6-3 6-1 to world number 81 Damir Dzumhur.
The 21-year-old twice led by a set in hot conditions but the problem with his left leg helped Dzumhur fight back.
"I'm disappointed obviously because it's not my tennis that's let me down, it's my body," Edmund said.
Watson, 23, revealed after her match that she had also been troubled by physical issues.
"I came into the tournament with an abdominal strain," she said.
"As soon as it got important in that 5-4 game in the second set, I felt myself get tense and when I needed my serve today I couldn't reach up and hit it."
Agony for Watson - and an early exit
Watson, the British number two, made a great start against Babos by securing an early break for a 3-0 lead, but was soon broken back.
The Hungarian's aggressive serving game saved a set point at 5-6 as she produced two aces in a row, but Watson triumphed in the tie-break to secure a dramatic opening set than lasted 70 minutes.
At that stage, the advantage was with the Briton, who came out on top in a sumptuous 40-shot rally en route to earning what appeared a crucial break at 4-4 in the second set.
But 23-year-old Watson looked nervous as she served for the match, and lost her momentum as Babos reeled off three successive games to take the second set and level the match.
There was a further setback for Watson in the decider, as she was broken after pulling out of a shot when on top in a rally, in the mistaken belief that Babos had hit the ball long.
She broke back as Babos served for the match, and then pulled level at 5-5, only to fail in her next service game and lose the match.
Edmund's frustrating injury problems
Edmund, the British men's number three, called the trainer after the seventh game in the third set.
He managed to serve out for a 2-1 lead, but was no match for the Bosnian in the final two sets as his injury continued to hinder him.
Edmund, wincing and clutching his thigh, gave away five break points at 1-1 in the decider before succumbing and handing his opponent the decisive advantage.
The 21-year-old struggled to make it to the baseline to serve his final game, and a backhand into the net confirmed defeat in three hours and 12 minutes.
"You can't play full out because you lose confidence in your movement and when you do move you start to cramp up again," said the Yorkshireman.
"It was the same situation I felt in Davis Cup where I couldn't do anything.
"To beat these guys you have to be 100%. You can't play with your body cramping. It's frustrating."
Analysis - BBC correspondent Russell Fuller
"Watson said before this match that the short-term addition of Judy Murray to her coaching team put her in a 'super positive' frame of mind, and she played this match in a similar vein.
"She served for a straight-set victory in a match of absorbing rallies of up to 40 shots, but ultimately one of great disappointment as Watson lost in the first round for the third year in a row.
"Playing in plus-30 degree heat, Edmund started cramping as early as the third set. Cramp was also an issue in the Davis Cup final: nerves play their part, and the 21-year-old knows it is something he needs to address."
What about the other British players?
British number one Andy Murray begins his campaign against German teenager Alexander Zverev on Tuesday.
His match will be the second of the day on the Margaret Court Arena (01:30 GMT approx).
British number one woman Johanna Konta takes on Venus Williams in the second match on Rod Laver Arena (01:30 GMT approx).
Dan Evans is also second on Court 13 for his match against Spain's Feliciano Lopez and is followed on court by Aljaz Bedene, who faces American Steve Johnson.