World number one Andy Murray was below his best but got past Illya Marchenko in straight sets in the Australian Open first round.
Murray struggled for large periods in hot conditions at Rod Laver Arena before completing a 7-5 7-6 (7-5) 6-2 victory on Monday.
It still took a draining two hours, 47 minutes for the Brit to progress at Melbourne Park as he set up a second-round clash against Russian teenager Andrey Rublev.
Murray made a nervous start - serving three double faults in the opening game - and he coughed up a break lead, taking 55 minutes to close the opening set.
The three-time grand-slam champion and five-time runner-up in Melbourne struggled with his serve throughout, making his life harder than it should have been against the world number 95.
Marchenko was aggressive in the second set, coming to the net frequently and taking a 3-1 lead he would give up.
Despite a mini-break to start the tie-break, Marchenko lost four straight points and his chances of an upset win.
The heat seemed to have taken the energy out of the Ukrainian, with Murray cruising through the third set.
Murray  bt Marchenko 7-5 7-6 (7-5) 6-2
Murray - 25/27
Marchenko - 46/62
Murray - 10
Marchenko - 6
BREAK POINTS WON
Murray - 6/8
Marchenko - 3/5
FIRST SERVE PERCENTAGE
Murray - 48
Marchenko - 54
PERCENTAGE OF POINTS WON ON FIRST/SECOND SERVE
Murray - 83/43
Marchenko - 66/41
Murray - 115
Marchenko - 96