Rory McIlroy has delivered the most withering criticism of golf’s inclusion in the Olympics, suggesting the sport was irrelevant in the context of the Games and also admitting he was “not sure” whether he would even be watching it.

Golf returns to the Games for the first time in 112 years in Rio but the four-times major winner last month declared himself unavailable, citing concerns over the Zika virus and the associated health risk he was unwilling to take. The world No3, Jordan Spieth, followed suit yesterday, joining McIlroy, the world No1, Jason Day, and No2 Dustin Johnson in missing the event.

At Royal Troon , where Rio matters completely overshadowed the buildup to Thursday’s Open, McIlroy was irked by being asked Olympic questions. After ambivalence towards whether he would be an interested onlooker, McIlroy, when asked which events at Rio he would watch, said: “Probably events like track and field, swimming, diving, the stuff that matters.”

The 27-year-old objected to the suggestion he had sold his sport short by refusing to play in Brazil. “I don’t feel like I’ve let the game down at all,” he said. “I didn’t get into golf to try to grow the game. I got into golf to win championships and win majors. All of a sudden you get to this point and there is a responsibility on you to grow the game and I get that. But at the same time that’s not the reason I got into golf. I got into golf to win. I didn’t get into golf to get other people into the game.

“I get where different people come from and different people have different opinions but I’m very happy with the decision I’ve made and I have no regrets about it.”

In one of the most memorable pre-tournament conferences of any Open, McIlroy had earlier taken aim at golf’s approach to drug testing. “I, on average, probably get tested four to five times a year, which is very little compared to the rest of the Olympic sports,” he said. “I haven’t been blood tested yet. I’ve got to know a lot of athletes over the years, I think drug testing in golf is still quite far behind some of the other sports, whether it be coming to their houses and doing blood and urine.

“HGH [human growth hormone] you can’t really pick it up in a urine test. I could use HGH and get away with it. So I think blood testing is something that needs to happen in golf just to make sure it is a clean sport. I think if golf is in the Olympics and wants to be seen as a mainstream sport, it has to get in line with the other sports that test more rigorously.”

McIlroy spoke immediately after Spieth, who said his call not to travel to Rio was “the hardest decision I’ve had to make in my life”. Spieth, in contrast to McIlroy, gushed about the merits of golf in the Olympics. “This was something I very much struggled with,” the American said.

“Why was it so hard? Because I’m a huge believer in Olympic golf. I’m a huge believer in playing for your country. I absolutely look forward to summer and winter Olympics, it’s the most exciting sporting event for me to watch on TV and to have a chance to be a part of it is something I definitely look forward to trying to do. I do hope to play in four or five, you name it, Olympics representing the United States in the future.

“This year I just had to try to weigh a risk that doesn’t present itself every year, and just at the time I had to make the decision, I just felt this was the right move for me. Not everybody’s going to understand. Nobody’s going to understand what it’s like in my shoes.”

Spieth was anxious to point out Zika was not the sole reason for his withdrawal. “I’m not specifically pinpointing any one thing in my health concerns,” he said. “You guys [the media] have put that without me saying it. I’m strictly health concerns as a whole. That’s not the only one.

“I can understand why people are sceptical [as to Spieth’s motives]. They’re as passionate about the Olympics as I am. They also are not in my shoes. So I feel that many, if not all of you, would have made the same decision if you were in my shoes. Whether you believe it or not, so be it.

This is just something that was very challenging for me. I very much struggled with it. I certainly didn’t want to have to do this during major week. This decision will loom over me throughout the Olympic Games. I will be, I’m sure, at times pretty upset I’m not down there.”

Danny Willett, the Masters champion, will play in the Games and remains relaxed about Zika. “You’ve got more chance of getting malaria in South Africa than you have in getting Zika when you go to Rio,” he said. “If there are Olympic Games in Johannesburg would guys pull out because of malaria? I don’t know.”