Or was it the court?
The match had all the makings of a routine Federer victory after the first set, which the Swiss great won with two service breaks and the loss of just one point on his serve.
That took great self-belief, he added, knowing that he had never taken a set off 20-time major victor Federer in four previous meetings.
Anderson, the first South African to reach the last eight since Wayne Ferreira in 1994, was steadfast though and did what no man had done at Wimbledon since last year's semi-final when he broke Federer's serve early in the second set.
And he didn't stop there. In the final set, Anderson won more big points than Federer lost, but the opportunities were there for the No. 1 seed and he kept letting them get away.
U.S. officer quits after harassment over Puerto Rico shirt
Irizzary was wearing a shirt made to look like the Puerto Rico flag, with the words "Puerto Rico" written on the top. He added that the park staff had apologised directly to Ms Irizarry and refunded the money she paid for her permit.
"I just kept on telling myself that I had to keep on believing".
If Nadal wins Wimbledon and retains his US Open title later in the year, there will only be one major separating him from his old foe Federer.
Federer had been pursuing a 13th Wimbledon semi-final and a 44th appearance in the last four of a grand slam.
Federer saved a set point in the fourth with a flying forehand but Anderson replied with a whipped victor of his own to ensure a decider would be needed.
Federer raced to a two-set lead but Djokovic forced a fifth before running out of steam, both physically and mentally. It set Federer off - he remained heated by the overturn ("That one cost me the match, eventually", Federer said later) and he began jawing at the chair umpire to complain about a number of things, including how long Del Potro was taking to challenge.
Not that Anderson is anything other than an elite tennis player. "I couldn't really get the rallies going the way I wanted to, especially the 1-2 punch wasn't working at all today".
Much to tennis fans all over the world's delight, the legend, at least now, seems to want to come back and try again.
North Koreans Miss Meeting About US Soldier Remains
Between 1996 and 2005, some 33 recovery operations were conducted in North Korea which saw 200 sets of remains returned. Although Pompeo insisted progress continued to be made, North Korea accused the U.S. of making "gangster-like" demands.
"It's disappointing losing the next two sets after winning the first two and having match points", said Federer. The 2017 U.S. Open runner-up triumphed in 4 hours and 14 minutes.
Djokovic now awaits Rafael Nadal or Juan Martin del Potro and on Friday will contest his first All England Club semi-final since 2015. In the penultimate game, Federer hit a shot that went close to the line, the crowd gasped, but Anderson was able to get the ball back in play.
Federer, who turns 37 next month, had been utterly dominant on his way to the last eight, swatting off Dusan Lajovic, Lukas Lacko, Jan-Lennard Struff and Adrian Mannarino in a combined total of little more than six hours on court. "I felt like I did some good business here in the past already", he said.
"I'm not quite sure what to say right now but down two sets, I really just tried my best to keep fighting", Anderson told the BBC in his post-match interview.
"Well, maybe wasn't my best, but I thought I was playing good enough", said Nishikori.
How Judge Brett Kavanaugh’s confirmation could affect Roe v. Wade
However, the news of this endorsement was undermined by another letter signed by Kavanaugh's fellow alumnus of Yale Law School. It would be the height of naivet to believe that Republican President Donald Trump and the GOP majority in the U.S.