The 22-year-old Greek pulled off the feat in the last eight at the Australian Open in Melbourne after just over four hours of battle.
Federer was the first in March 2005 when Tsitsipas was still at primary school. The comeback took place in the final at the Miami Masters.
Fognini succeeded in the third round at the US Open in 2015.
Nadal, the second seed, went into Wednesday night’s encounter against Tsitsipas on Rod Laver Arena having won six of their seven meetings on the senior tour since 2018.
Two years ago in the semi-final Nadal pulverized him 6-2, 6-4, 6-0. And Wednesday night’s match appeared to be heading in a similar direction after the Spaniard took the opening two sets 6-3, 6-2 in 37 and 41 minutes respectively.
Both men held their serve throughout the third set which went to a tiebreak. Three unforced errors swung the shoot-out towards Tsitsipas and he wrapped it up seven points to four after a Nadal backhand flew long.
Revenge
Tsitsipas got the crucial break in the fourth set during the ninth game and he held his serve to win it 6-4 and level the tie at two sets apiece after three hours and nine minutes.
Tsitsipas entered Federer-Fognini territory 50 minutes later after winning four consecutive points to claim Nadal’s service and a 6-5 lead.
A service winner brought up his first match point. A forehand error accounted for that before a winner off the same wing notched up the second.
That was lost after Nadal smashed away a second service. The Spaniard then carved open a break point to take the set into a tiebreak.
Tsitsipas saved that and eventually took the spoils on his third match point when a Nadal forehand slumped into the net.
“It’s an unbelievable feeling to fight and give my all,” said Tsitsipas. “I started nervously but I flew like a bird and everything worked for me.”
Wait. The thinker @steftsitsipas without....thoughts? 🧘♂️
— #AusOpen (@AustralianOpen) February 17, 2021
Mark this day on the calendar 😉#AusOpen | #AO2021 pic.twitter.com/JqbjA5NdW2
Nadal, who had been seeking a record 21st Grand Slam singles title, was munificent in defeat.
"Well done for him, he played better than me probably in the important moments. I tried my best in every single moment.
"I think I stayed positive all the time during the match, fighting, and it was not enough. Sometimes it's enough, today was not enough.”
Tsitsipas will meet the fourth seed Daniil Medvedev in Friday’s semi-final after the Russian beat his eighth seeded compatriot Andrey Rublev 7-5, 6-3, 6-2.
“He’s an opponent who is in good shape,” said Tsitsipas. “He will give me a difficult time on court.”
