Australian Open: Andy Murray moves through after a fight

Murray shouted “Wake up!” during one of many frustrating moments on Rod Laver Arena but a dozy display proved sufficient as the Scot sealed a 7-5 7-6 (7/5) 6-2 victory.

He will face Russian teenager Andrey Rublev, the world No 152 who had earlier registered a surprise win over Yen-Hsun Lu.

Murray, walking out on court at just after 3pm local time, was not addressed as ‘Sir’ in the announcer’s introduction but that will have been of little concern to the top seed, who insisted in his post-match interview that “Andy is definitely fine”.

Instead, the Briton is likely keen to continue where he left off last season as he chases his first title in Melbourne, where he has reached the final five times but never been crowned champion.

The 29-year-old knows he will have to play far better than this if he is to lift the trophy a week on Sunday, after a scruffy performance that included 27 unforced errors, three conceded breaks of serve and a tendency to adopt the kind of careful, cautious tennis that will run him into trouble against more proficient opponents.

Marchenko, ranked 95th in the world and wearing his cap back to front, certainly offered a stern opening test, his exuberant shot-making and refusal to give in courting much support from an appreciative Australian crowd.

But baking hot conditions, with temperatures reaching 32 degrees Celsius, took their toll on the Ukrainian, along with Murray’s superior experience under pressure, which ultimately proved decisive.

Marchenko’s early break felt like little more than Murray blowing out the cobwebs, particularly when the Scot broke back before taking a 5-3 lead.

His shots, however, were loose and his energy lacking, and Marchenko came again, deservedly breaking a second time after picking up a deft forehand volley.

Murray did just enough to edge the opening set, when Marchenko over-reached on a forehand, but seeds of confidence had been sewn in his opponent, who seized another break early in the second.

Frustrated, Murray bellowed to himself, and perhaps to his box, “Wake up!” before adding, “This is a grand slam guys, come on”.

Murray often needs a dose of agitation to jolt himself into action, however, and so it proved as he broke back for 4-4 before a brilliant top-spin lob, clipped on the run, put him 6-5 ahead.

Marchenko, who had missed a break point in the previous game, extended Murray to a tie-break but he wavered under pressure as three missed forehands helped Murray to a 4-1 lead.

There was no way back as Murray converted his third set point to move two sets clear and while Marchenko took a toilet break, perhaps to refocus, the rest of the contest was one-way traffic.

Murray broke twice to storm into a 5-1 lead in the third set and - when a final Marchenko forehand drifted long - his progress was confirmed in two hours and 47 minutes.

Aljaz Bedene became Britain’s first casualty after he lost in four sets to Dominican veteran Victor Estrella Burgos.

Estrella Burgos, who turns 37 later this year, is the fourth oldest singles player in the men’s draw in Melbourne but he proved too strong for an inconsistent Bedene, winning 7-6 (9/7) 7-5 0-6 6-3.

It is the fifth time in a row Bedene has lost here in the opening round while world No 103 Burgos goes through to face Australian Bernard Tomic.

Simona Halep fell victim to the first shock after the No 4 seed was dumped out by American Shelby Rogers.

Halep had been one of the favourites to challenge for the title in Melbourne but the Romanian was beaten 6-3 6-1 by Rogers in the tournament’s curtain-raiser on Rod Laver Arena.

Garbine Muguruza and Venus Williams avoided similar upsets but both were made to work hard as Muguruza edged past Marina Erakovic 7-5 6-4 while Williams beat Kateryna Kozlova 7-6 (7/5) 7-5.