Jack Sock became the youngest American man to reach the French Open last 16 since Pete Sampras 22 years ago, with a spirit fired by a pair of frightening family health scares.
At the start of the year, Sock, the world No.37, was at the bedside of his brother Eric who had been diagnosed with Lemierre’s Syndrome.
The rare disease, caused when an infection from a sore throat builds in the lungs, could have been fatal.
When Sock started his season at Indian Wells in March, he took to the court with the words “For you, Eric” penned into his tennis shoes.
Older brother Eric, a former university player in Nebraska and a tennis coach, spent the best part of two weeks in intensive care with Jack constantly at his bedside.
“When I was in the hospital next to the bed with my brother, it was a very tough time for not only myself but my family,” recalled Jack on Saturday after a 6-2 6-1 6-4 win against Croatian teenager Boran Coric put him into the last 16 of a grand slam for the first time.
“It was more motivation. He got through that, and it’s pushing me out on the court, teaching me things that maybe I didn’t know in the past.
“He’s able to get through that, makes the things on the court that I would maybe usually get frustrated with that don’t seem as big anymore. It helps me play a little bit more relaxeed tennis.”
In Paris, Sock is now sporting another message of support on his footwear.
This time it’s “4uGPa” in honour of his grandfather who is suffering from Alzheimer’s.
Immediately after his win over Coric, he called the centre in Atlanta who are caring for his grandfather.
“My aunt and my grandmother are with him, bedside, and they put the phone up to his ear so I could say some words and hopefully could hear me,” said Sock.
“He can’t respond, he’s got tubes down his throat. He’s battling with Alzheimer’s right now.
“He’s lost a bunch of weight and not looking great. But it’s a part of life, you know. It’s something that everyone goes through.”
On the court, Sock will have to get past nine-time champion Rafael Nadal on Monday in his fourth-round clash.
It will be Sock’s first encounter with the Spaniard, although the respective merits of their forehands have often been compared.
“It will be kind of a chess match and who can find the forehand first and kind of open up the court,” predicted the American.
Nadal is wary of the dangers posed by Sock, who beat 10th seed Grigor Dimitrov in the first round before getting past Spanish claycourter Pablo Carreno Busta.
“He’s a great player,” said Nadal.
“He has an amazing forehand, very good serve, and can play very aggressive and is dangerous. I know I have to be very solid.
“I will try not to let him get into good forehand positions, because I am going to be in big trouble.”