SIR Andy Murray admits he had to dig deep as the below-par Briton beat Illya Marchenko to reach the Australian Open second round.

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 now face Russian teenager Andrey Rublev, the world number 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".

Read more: Murray progresses to Australian Open second round after win over Marchenko

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.

"I don't think it was the best match, to be honest," Murray said.

"The conditions there were pretty different to what we've been practising on. The last week's been pretty cool. A lot of days, it's been overcast. The temperature of the court is much cooler.

"When it's like that, the ball is bouncing a bit lower, (it's) a bit easier to control the ball. 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. It just was tough."

Read more: Murray progresses to Australian Open second round after win over Marchenko

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.

Rublev will offer an altogether different proposition, coming in as one of the brightest talents on the tour and having previously played in only one grand slam main draw.

"I know a little bit about him," Murray said. "I've never hit with him or played against him but I've seen him play before and he goes for it. He doesn't hold back. He hits a big ball.

"I saw him play a couple of years ago at the US Open against (Mikhail) Youzhny. I watched a bit of his match there. I thought he was very good, a clean ball-striker. Like I said, he goes for it.

"Obviously when you get out there, things look a little bit different than they might on the TV or on the video. But I'll try to watch a bit over the next couple of days and hopefully go in with a good strategy.

"I'll need to work some things out myself when I'm out there."