When Wimbledon started, Marin Cilic was looking at a draw that could have pitted him against Rafael Nadal in the quarterfinals and Andy Murray in the semifinals. The end was brutal, Querrey running through Murray to record a 3-6, 6-4, 6-7, 6-1, 6-1 win.
Federer returned from a six-month knee surgery lay-off to dramatically win the Australian Open in January, his first grand slam title since the day he denied Murray at Wimbledon. Their match featured many competitive sets, however, Cilic often had the goods late in the individual sets.
American Sam Querrey has a knack for toppling defending champions at Wimbledon.
The top seed twice led by a set on Centre Court, but the defence of his title came to an end in a 3-6 6-4 6-7 (4-7) 6-1 6-1 defeat to the American, who previous year knocked out Novak Djokovic in round three.
Querrey, the 24th-seeded American, will have to cause a sizeable upset to prevent that happening.
"A physical issue then becomes a distraction and even though Querrey was down two sets to one, you still felt he had the energy to keep making Murray work".
After winning the first set, Querrey fought back to win the second but Murray was able to take the decisive third set in a tiebreak. He entered the tournament after pulling out of two exhibition matches citing a sore left hip.
Querrey is playing in his third consecutive five-set match at Wimbledon. However, while Federer has not dropped a set, the big Canadian needed five sets to see off highly-rated German Alexander Zverev in the last-16.
"I knew I wasn't going to do any major damage to my hip by playing". Querrey, the No. 28 seed, will face Croatian Marin Cilic on Friday.
He would win 12 of the match's final 14 games, taking advantage of a clearly-hobbled Murray to stun the British crowd and knock out the defending champion. The Swiss, 35, played his best tennis of the tournament to dismantle the big-serving Canadian who knocked him out at the semi-final stage a year ago.
The niggle has prevented the world No 1 from pushing through on his first serve - an area which will be closely scrutinised against Querrey today. The development means that Wimbledon 2017 will feature a first-time finalist.
Querrey's shocked the tennis world before; past year, he beat No. 1 at the time Novak Djokovic in the third round in the Wimbledon third round (but was beat in the quarters).
The world number one joined Venus Williams in calling for earlier starts to allow two men's and two women's matches on the big show courts, Centre Court and Court One.