|Australian Open 2017|
|Venue: Melbourne Park, Melbourne Dates: 16-29 Jan|
|Coverage: Live commentary every day on BBC Radio 5 live sports extra plus TV highlights on BBC Two from 21 January; live text on selected matches on the BBC Sport website.|
Britain's Andy Murray won his first Grand Slam match since becoming world number one but was given a stern test by world number 95 Illya Marchenko.
A clearly frustrated Murray was far from his best but reached the second round of the Australian Open with a 7-5 7-6 (7-5) 6-2 win over the Ukrainian.
The Scot, attempting to win his first Australian Open title after five final defeats, won in two hours 48 minutes.
Fellow Briton Dan Evans beat Facundo Bagnis of Argentina in straight sets.
Evans, the world number 51, saved three set points before winning the opener in a tie-break, then broke Bagnis in the first game of the second set.
A break of the world number 65's serve in game nine gave Evans the second set, and he wrapped up a 7-6 (10-8) 6-3 6-1 victory to set up a second-round match against Marin Cilic.
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Murray errors boosted Marchenko
Murray, 29, made a nervy start and lost the first game with three double faults and a forehand error, but took control to serve for the set at 5-3.
However, Marchenko broke the Scot again to draw level, only for Murray to raise his intensity and take the set after 55 minutes.
Murray became increasingly frustrated in the second set, berating himself for his errors and unusually sluggish movement, as his opponent grew in confidence.
The Ukrainian, also 29, hit a series of powerful forehands and deft volleys to take the lead in the set.
Murray had to fight hard to force a tie-break, but once again the top seed did enough when it mattered to win the set after a marathon 76 minutes in hot conditions.
The gruelling effort seemed to affect Marchenko in the third set and Murray took advantage to win it without any complications.
He faces Russia's Andrey Rublev in round two.
"I don't think it was the best match," said the Wimbledon champion. "The conditions were pretty different to what we've been practising in.
"Last week's been pretty cool. When it's like that, the ball is bouncing a bit lower and it is a bit easier to control. I was a bit tentative because of that.
"And I didn't serve that well either. So you end up having to work really hard on a lot of your service games when it's like that."
BBC tennis correspondent Russell Fuller
It was a very hot afternoon and therefore I think you could say Murray expended a little more energy than he would wish.
His first serve will be a concern - it can't be easy serving in the sun - but the heat is not really a huge factor for him.
All in all, he looked in pretty good spirits. I don't think he'll be hugely concerned but there are things to work on.
First-round exit for Bedene
British number four Aljaz Bedene lost 7-6 (9-7) 7-5 0-6 6-3 to 36-year-old Dominican Victor Estrella Burgos.
Bedene, ranked 108 in the world, was 5-2 up in the opener but Estrella Burgos took the first two sets.
The Slovenia-born Briton eased through the third set, but Estrella Burgos progressed after three hours and nine minutes.