Alexandr Dolgopolov scored a fine five-set win over the excellent German Jan-Lennard Struff to advance to the second round of the US Open on Wednesday – then reacted furiously to questions about allegations of match-fixing in his first-round loss in Winston-Salem last week.

The 28-year-old Ukrainian, who has earned $498,957 in a middling season and $6.4m in 12 years on the Tour came under investigation by the Tennis Integrity Unit because of suspicious betting patterns in his match against world No114 Thiago Monteiro.

On day three here, he played some inspired tennis to beat 46th-ranked Struff 3-6, 6-3, 6-2, 1-6, 6-3 in two-and-a-half hours on Court 16, and next meets 15th seed Tomas Berdych, who took three quick sets to beat the American Ryan Harrison.

However, there were no questions about Dolgopolov’s win over Struff when he came into his press conference.

When asked for his reaction to the spike in betting on last week’s match – which the Spaniard won 6-3, 6-3 before losing to the world No40 Paolo Lorenzi in the second round – Dolgopolov replied: “You want my honest answer? I don’t give a fuck to be honest, because it’s like a circus.

“I think I should be asking you guys how you feel about your fellow journalists writing about maybe there’s a fix in the match because there is a market. I read the article. It was like the statistics of my break points. Are you serious? You are going now to the statistics and saying it might be fixed because there is a market? Are you writing news or fairytales? I go on social media and every time I have to delete 10 messages because people are doing threats, stuff to the family.

“So, for me, I don’t want to even talk about it. I talked to the TIU. I respect their work. I gave all the information needed. At the end of the day, what’s going to happen is I’m not involved in anything. That’s going to be what happens and these guys are still going to write that bullshit. For me, writing those things before there is an investigation is silly.”

He was in no mood to be placated, and added: “The press talking about match fixing. Let’s talk about facts. There is a TIU that does their job. If they find something, good, let’s talk about it. Before that it’s a pity that the guys are writing and hurting people’s image without anything, just a betting pattern. How do I have anything connected with that? A guy got drunk who went to bet one million and I have to answer every time or someone has to answer different players.”

He insisted he had tried his hardest against Monteiro but was below par physically.

“I was giving my best effort. I wasn’t playing my best. I was doing a lot of practice before [arriving at Flushing Meadows] because I wasn’t feeling good against [Nick] Kyrgios in Cincinnati. I was physically weak. I blacked out in that match. I wasn’t happy with my physical condition and I knew by New York I needed to get some work done. Obviously you want to be ready for the US Open at the tournament before. I was working hard and playing [despite] tiredness.

“I’ve spoken to the [TIU] a few times. They gather a lot of information and it’s strange they always find nothing. There’s so much match-fixing we hear about, so many markets going on, and they never find anything? That’s surprising.”

Asked if he had ever been approached by gamblers, he said: “Er, no, not really. I don’t have a lot of friends on social networks. If you give your phone too many times, probably … But, no, not that I remember.”

When it was put to him that his answer sounded like he had been approached, he fumed: “Sounds like why? You want go to predictions? You want to ask a third time? I come here after a five-set match and all you ask is about betting patterns. Can you ask something normal? I don’t want to answer stupid questions.”