Rory McIlroy has heightened speculation surrounding his return to action by posting a video which shows him working out in the gym without any apparent discomfort from his injured ankle.

McIlroy has not played since suffering a “total rupture” of ligaments in his left ankle during a game of football with friends on July 4th, an injury which ruled him out of the Scottish Open and the defence of his British Open and WGC-Bridgestone Invitational titles.

The 26-year-old has yet to say whether he will be able to defend the US PGA Championship next week and on Tuesday his publicist denied reports he had scheduled a practice round at Whistling Straits on Saturday.

However, on Wednesday McIlroy posted a video on his Instagram account in which he was seen balancing on his left leg and twisting and throwing a gym ball to mimic the actions of the golf swing.

Alongside the short video clip, McIlroy wrote: “Working hard every day to come back stronger #dontmindthegrind.”

McIlroy will be replaced as world number one by Masters and US Open champion Jordan Spieth if the 22-year-old American can win his first World Golf Championship title at Firestone Country Club this week.

It was at the same event that McIlroy overturned a three-shot deficit to Ryder Cup team-mate Sergio Garcia in the final round 12 months ago to move back to the top of the rankings.