Before the Australian Open, not many in Australia would have heard about the aptly-named American tennis player Tennys Sandgren.

Now that the underdog has reached an unprecedented spot in the Australian Open quarter-finals —beating Austrian eighth seed Dominic Thiem to get there — Sandgren is experiencing far more spotlight on his career, as well as his social media activity.

And several of his tweets have now raised questions over his political views, after he argued over the Pizzagate conspiracy and mused over former US presidential candidate Hillary Clinton and her supposed involvement in alleged satanic rituals.

Sandgren also recently retweeted white nationalist Nicholas Fuentes — who went along to the Charlottesville rally in 2017 — and follows a host of right-wing figures on Twitter.

In a now-deleted tweet dated November 22, 2017, Sandgren described the Pizzagate conspiracy theory as "sickening and the collective evidence is too much to ignore".

The tweets in question have now been taken down in something of a Twitter purge, with Sandgren's most recent tweet dating back all the way to November 20, 2013.

The tweets have prompted pointed questions at Sandgren's post-match press conference, with the social media posts now providing a huge distraction to a career-best performance at a grand slam event.

Tennys Sandgren insists his engagement with certain individuals on Twitter does not equate to endorsements. ( AP: Ng Han Guan )

Asked by a reporter if there was a pattern to his tweets, Sandgren said he was not concerned about being connected to controversial figures on social media.

"Who you follow on Twitter, I feel like doesn't matter even a little bit. What information you see doesn't dictate what you think or believe and I think it's crazy to assume that," Sandgren said.

"To say 'well he's following X person so he believes all the things that this person believes', I think that's ridiculous. That's not how information works.

"If you watch a news channel you wouldn't then say that that person who's watching a news channel thinks everything that that news channel puts out. You wouldn't think that.

"I don't think that any kind of engagement in that way dictates that you then are right in there with that particular person. I don't think it works that way and I don't see it as working that way.

"I mean, you can ask me about my beliefs on things, that's cool. But I think to … just say 'well, you follow this person'. You can ask me who I am and I'm perfectly fine answering those kinds of questions."

Sandgren finds some alt-right content 'interesting'

The Pizzagate conspiracy — an unfounded online theory about a paedophile ring linked to Ms Clinton, claiming prominent Democrats were harbouring child sex slaves at Washington's Comet Ping Pong restaurant — saw a man sentenced to four years in prison for entering the restaurant armed with an assault rifle and firing the weapon.

Tennys Sandgren has surprised everyone with his run to the Australian Open quarter-finals. ( AP: Vincent Thian )

Sandgren's Twitter bio reads: "I write all tweets on a napkin first to order my thoughts.. likes/rtwts are not endorsements."

He insisted he does not support the alt-right movement, but he found "some of the content interesting".

"I find some of the content interesting, but no I don't [support them]. Not at all," Sandgren said at his media conference.

"No, as a firm Christian, I don't support things like that, no. I support Christ and following him and that's what I support."

Sandgren has also argued with former US player James Blake — an African-American — about racism in the United States, tweeting "I just don't know how a country that practices systemic racism elected a black pres, twice".

What is Pizzagate? An internet conspiracy theory that emerged during the 2016 US presidential election

An internet conspiracy theory that emerged during the 2016 US presidential election Theory claims leaked emails from a former aide to Hillary Clinton contained coded messages about a paedophile ring

Theory claims leaked emails from a former aide to Hillary Clinton contained coded messages about a paedophile ring Former presidential candidate Ms Clinton was alleged to have been at the centre of it, which allegedly involved human trafficking in a number of US restaurants

Former presidential candidate Ms Clinton was alleged to have been at the centre of it, which allegedly involved human trafficking in a number of US restaurants Washington's Comet Ping Pong restaurant was named as one of the businesses allegedly involved with the group

A little-known player outside of the United States, Sandgren's ranking dropped to as low as world number 714 after hip surgery sidelined him for six months back in 2014.

Now ranked number 97 in the world, his Australian Open run is career-best territory for Sandgren at a major, having never got past the first round at the US and French Opens. He has yet to get past the qualifying phase for Wimbledon.

His only two wins over top-10 opponents have both come at this year's Australian Open, clinching a huge shock win over Stan Wawrinka 6-2, 6-1, 6-4, before his fourth-round victory over Thiem.

On his ATP bio, he states his love of video games — particularly League of Legends and Hearthstone — so much so his favourite sports team is League of Legends eSports team Unicorns of Love.

Sandgren will face South Korean surprise package Hyeon Chung for a place in the Australian Open semi-finals on Wednesday night.