Jack Sock has a new perspective about life on the tennis court after his brother had a narrow escape from a life-threatening illness last year.

Sock, who will face David Ferrer in the ASB Classic semifinals tomorrow, is coming off a career-best year in 2015, where he won his first ATP title and reached No26 in the world.

Sock - who is known for his charismatic on court persona - says his success is down to a reality check after his older brother, Eric, was hospitalised with a rare illness last January.

"With my brother being in hospital it made me take a step back ... it gave me a new perspective on life in general," said Sock. "They said my brother was 24 hours away from not making it and it really opened my eyes. I realised that tennis is my career and I love playing but there are other things in life."


Eric Sock, who played high school tennis alongside Jack, was rushed to hospital after complications from pneumonia.

He was diagnosed with Lemierre's Syndrome, a rare (sometimes fatal) bacterial infection that was attacking his liver, kidney and heart. Eric was on life support for eight days - and Sock who was at home due to an injury - was by his side.

After that Sock has found a new tennis groove, lifting the trophy in Houston last year, reaching another final in Stockholm and compiling a 35-18 win loss record for the year.

He showed his powers of recovery today, coming back from an awful start to trump world No12 Kevin Anderson 1-6, 6-4, 6-4 in 98 minutes.

"He came out firing, didn't miss many first serves," reflected Sock. "From the ground he was playing really well but I was able to get a rhythm at the end."

The 23-year-old also showed his lighter side on court, tossing one of his socks to a surprised fan at the end of a match, a gesture he hopes might become his trademark.

"I'm trying it out for a bit to see how people react," said Sock. "A few guys have their signature things. I thought with such a unique last name it might be something clever and fun."

But Sock will need to be all business tomorrow, looking for just his second win over a top 10 player in 16 attempts.

"I'll have to be the aggressor, dictating points," he said. "If not [Ferrer] is very good at getting balls back, and making a lot of balls."