Andy Murray suffers defeat during his comeback match in Abu Dhabi

Serious question marks remain about Andy Murray's fitness ahead of the Australian Open after he was beaten 6-2 by Roberto Bautista Agut in a one-set exhibition in Abu Dhabi.

The Scot, who is working his way back from hip problems, stepped in after Novak Djokovic's own Melbourne hopes were plunged into doubt when he was forced to withdraw having experienced more pain in his elbow.

Like Murray, Djokovic has not played a competitive match since Wimbledon and had been due to make his comeback with a semi-final against world number 20 Bautista Agut at the Mubadala World Tennis Championship.

Murray has given little away either about the precise nature of his hip injury or his recovery but delaying his departure to Australia, having originally intended to travel before Christmas, did not send a positive message.

The 30-year-old had intended just to practise with the players competing in the tournament in Abu Dhabi, which is staging the pre-season event, but he answered the organisers' call following Djokovic's withdrawal.

That in itself seemed positive but from the start it was clear Murray was well short of his best.

The limp that was such a talking point at Wimbledon was still very much in evidence and his movement was hampered when dragged out wide on his forehand side.

A helpful net cord allowed Murray to get on the board in the fifth game when he had faced points for 5-0, and he did improve in the latter stages.

The Scot said in an on-court interview broadcast by Eurosport: "I felt better as it went on. I was a little bit slow at the start. Roberto is one of the best players in the world and when you haven't competed at this level for a while it takes a long time to get back. I need to keep improving for sure."

Some rust was, of course, inevitable, and Bautista Agut is a high-class competitor with a match already under his belt, but Murray now has some big decisions to make.

The three-time grand slam champion is due to make his competitive return at next week's Brisbane International, while the Australian Open starts in just over two weeks' time.

Djokovic admitted he could be forced out of the new year's first grand slam after suffering a dispiriting setback.

The Serbian had appeared the furthest forward of all men's tennis' walking wounded, with Rafael Nadal, Stan Wawrinka and Milos Raonic all pulling out ahead of the tournament.

But in a statement on his official personal website, Djokovic said: "I am terribly disappointed that I am forced to withdraw from the Mubadala World Tennis Championship. Unfortunately, in the past few days I started to feel pain in the elbow and after several tests, my medical team has advised me not to risk anything, to withdraw from the tournament and to immediately continue with the therapies.

"Now I need to accept this situation, and to wait for the results of the therapies, in order to start playing tennis again and getting back to full rhythm.

"This might affect the start of the season and the tournament plan, but the decision will be made in the following days."

Bautista Agut will face Kevin Anderson in the Abu Dhabi final on Saturday. The South African maintained his 100 per cent record against Dominic Thiem with a 7-6 (8/6) 6-4 victory.