Doubts are starting to emerge over Andy Murray's participation at the 2018 Australian Open as he is still training in the UK.

Murray was already expected in Australia before Christmas in a bid to acclimatise to the country and undergo preparation ahead of his return to action at the Brisbane Open.

"My plan is to do a couple of weeks in Miami and then go to Australia very early, much earlier than I have done in the past," Murray had said following his charity match in Glasgow in early November.

"Coming into the beginning of the new year, I will be at a bit of a disadvantage because I have not played matches for a long time.

"So, if I can go there a little bit earlier to get used to the conditions, a bit sooner than some of the other players, that might help level it up a little bit for me."

However, according to The Telegraph, the Briton is still training at the All England Club's facilities in Wimbledon and Raynes Park.

While Murray's body has not broken down, there are fears that he is behind schedule due to continued problems with a hip injury.

The 30-year-old started the year as the top ranked player in tennis for the first time in his career following his win at the ATP Finals in London in November 2016. However, poor form and injuries have hindered his calendar year with just the one title in Dubai and his best Grand Slam performance being a French Open semi-final exit.

Murray last featured at Wimbledon in July after his quarter-final loss to Sam Querrey and decided to take the rest of the year off to recover from the hip injury as he dropped out of the top 10 for the first time since 2014.

The former world number one was previously confirmed to take part in Melbourne for the 2018 Australian Open, which begins on 15 January. But with doubts still remaining on if he'll take part in the Brisbane Open, which begins on 1 January, the clock is ticking for Murray.