'That is troubling': Roger Federer in shock injury drama at Australian Open

Roger Federer showed glimpses of his tennis mortality against American world no.100 Tennys Sandgren in the Australian Open fourth round on Tuesday.

The Swiss champion was forced to call for a lengthy medical timeout during the third set, after dropping the second set in alarming fashion.

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As Federer stormed through the first set 6-3 it appeared as though everything was going according to script - but as Sandgren fought back in the second set, the world no.3 appeared to grow increasingly frustrated.

At one point Federer copped a code violation for an audible obscenity, leaving him in disbelief after one of the line judges approached the chair umpire to report it during the second set.

The match took its next dramatic turn in the third set, as Federer left the court for a medical timeout.

The 38-year-old appeared to be hampered by something after the first set, something that didn’t go unnoticed by Channel 9 commentators Jim Courier and Todd Woodbridge.

“Houston, we have a major problem here with Roger Federer,” Courier said.

“He is in major trouble here, physically. Not exactly sure if it’s back, groin, hip, whatever the treatment is, it’s real. He just doesn’t have it.”

Courier pointed out Federer’s serve was suffering the most due to the mystery ailment.

Federer returned to the court after the timeout, preserving his streak of having never retired mid-match.

“He has lost an immense amount (on his serve). 10% speed gone. That is troubling,” Courier said.

“He just can’t bend, Todd. There is no arch in his back right now. He can’t even move for that.

“He has been a superhuman. Not today and his body is betraying him.”

Federer looked to have recovered somewhat in the fourth set, forcing a tiebreak and saving seven match points, before taking the match to a deciding fifth frame.

Federer filthy after code violation

It was already an unusually dramatic outing for Federer, after he was given a code violation when a line judge overheard him swearing.

The 20-time Grand Slam champ was struggling against the American after easily taking the first set and was looking at going 3-0 down in the third set.

But things took a turn when Federer mumbled something and the line judge approached the chair umpire and signalled he had made an audible obscenity.

This did not sit well with the normally cool mannered Federer.