Indignation that he has not made it past the quarter-finals in any of the past six.
It didn't show in Djokovic's play, though, as he embarked upon another swing of four games in succession, holding Nishikori to three points in his next two service sets as he soared into a 4-1 lead.
"I had my chances", Federer said, "so it's disappointing". "I'm enjoying my Wimbledon journey".
"It's like that with the big servers", Federer said.
Anderson, who reached the U.S. Open final past year, saved a match point in the third set before recovering to beat the Swiss top seed 2-6 6-7 (5) 7-5 6-4 13-11 after four hours and 14 minutes on Court One.
But the 12-times major victor regained his cool sufficiently enough to safely take his place in the semi-finals for the first time since snaring his third title at The All England Club in 2015.
When Del Potro sent a forehand rifling down the line to take the third set, it seemed Nadal might be following Federer out of the tournament, but the World No.1 recovered superbly to triumph 7-5 6-7 (7/9) 4-6 6-4 6-4 and keep alive his hopes of an 18th Grand Slam title.
At Least One Dead After Helicopter Crashes Into Townhouses, Causing Massive Fire
The Federal Aviation Administration tweeted that Aviation Safety Inspectors arrived in Williamsburg around 7:30 Sunday evening. The impact of the crash sparked up a fire at the townhouse complex, which is surrounded by several other residential units.
His match against Nishikori will fall on the first anniversary of him having to retire from his 2017 quarter-final against Tomas Berdcyh with an elbow injury.
However, the 31-year-old has looked back to something approaching his best at Wimbledon. "I think it was great quality tennis and in the final set there were some wonderful points", said Nadal who was a 7-5 6-7 4-6 6-4 6-4 victor. "I'm a different person, different player today".
"You're saying in the point if I toss my racket like this I'm ruining the court?"
"I repeat that all those who supported Croatia against Russian Federation are psychopaths and mad, fit for being locked up in an asylum".
Novak Djokovic is feeling more optimistic after continuing his fine run at Wimbledon by reaching the quarter-finals.
Eight-time champion Federer has already won more Wimbledon singles titles than any other man, but was aiming to equal Martina Navratilova's all-time record. "Be honest", Djokovic asked. "It's always big challenge", said Nishikori.
"Just the way he moves, the way he conducts himself on the court is very impressive". The use of the slice backhand.
The 20-time Grand Slam champion appeared to be moving toward his fifth successive Wimbledon semifinal after taking the opening two sets. He made a couple of great shots but I managed to break and get back into the set.