Routed by Rafa, stunned by Stakhovsky - Federer's worst grand slam defeats

As the tennis world prepared for a US Open quarter-final blockbuster between Novak Djokovic and Roger Federer, unheralded Australian John Millman had other ideas.

The world number 55 defeated Federer in four sets at Flushing Meadows in the most remarkable upset of the tournament so far this year.

Federer has won 20 grand slams during his career, but Millman was not the first man to bring the Swiss great crashing back down to earth on one of tennis' biggest stages.

We've picked out five other occasions on which the 37-year-old was stunned at majors.

HUMILIATED BY RAFA (FRENCH OPEN 2008)

Federer may have made the final and gone down to the King of Clay at Roland Garros in 2008, but his defeat to Rafael Nadal was the worst of his career. A 6-1 6-3 6-0 scoreline told the whole story in a third consecutive French Open final reverse, the Swiss completely outclassed. "Roger, I'm sorry for the final," said an almost embarrassed Nadal.

TSONGA ROARS BACK (WIMBLEDON 2011)

Then six-time Wimbledon champion Federer looked on course for further glory as he led Jo-Wilfried Tsonga by two sets in the 2011 quarter-finals, before everything went so horribly wrong for the favourite. Federer did not create a single break point in the remainder of the match and went down 3-6 6-7 (3-7) 6-4 6-4 6-4 to the horror of his adoring fans at the All England Club.

FOLLOWING NADAL OUT (WIMBLEDON 2013)

With Nadal departing Wimbledon to world number 135 Steve Darcis in the first round, Federer's hopes of a second straight title - an eighth overall - were significantly boosted. But the defending champion soon followed his rival in crashing out at the All England Club. Sergiy Stakhovsky lost the first-set tie-break, but triumphed 6-7 (5-7) 7-6 (7-5) 7-5 7-6 (7-5).

SLUMP CONTINUES IN STRAIGHT SETS (US OPEN 2013)

Although it was not obvious at the time, 2013 would mark the beginning of a particularly tough stretch in Federer's career. He failed to arrest the slump early at the US Open and followed up his second-round Wimbledon defeat with a fourth-round humbling to Tommy Robredo. The Spaniard's improbable 7-6 (7-3) 6-3 6-4 victory meant he, and not Federer, faced Nadal in the quarters. Robredo won just four games.

SEPPI SCUPPERS MURRAY MEETING (AUSTRALIAN OPEN 2015)

Many tennis fans had already pencilled in Federer to face Andy Murray in the last eight of the Australian Open in 2015, yet the then four-time winner did not even make it past the third round. Italy's Andreas Seppi was Federer's conqueror as the Swiss failed to turn around an early deficit and was beaten 6-4 7-6 (7-5) 4-6 7-6 (7-5) in Melbourne.