TROON, Scotland -- Jordan Spieth dealt golf's return to the Olympics yet another blow Monday, telling International Golf Federation officials just before a news conference that he would not be playing next month in Brazil.

Spieth joins Jason Day, Dustin Johnson and Rory McIlroy in deciding to skip the Games, mostly due to concerns about the Zika virus that is prevalent in Rio de Janeiro. That means the top four players will be absent from the 60-player field, which was to be finalized following Sunday's update to the Official World Golf Ranking.

Jordan Spieth says he won't play in the Rio Olympics. AP Photo/Marco Garcia

Matt Kuchar will replace Spieth for the United States, which will have Rickie Fowler, Bubba Watson and Patrick Reed as its representatives because they are all ranked among the top 15 in the world.

Spieth, who was playing a practice round for The Open on Monday, is expected to discuss his decision during a Tuesday news conference.

"It's certainly disappointing that we've had so many withdrawals on the men's side,'' Peter Dawson, former head of the R&A and the president of the International Golf Federation, said during a news conference at Royal Troon.

The men will be represented by seven of the top 13 players in the world, with Watson at No. 5 being the highest-ranked. Among the other top 13 players going to Rio are Henrik Stenson, Masters champion Danny Willett, Justin Rose and Sergio Garcia.

But the tournament has become more about who is not going. Spieth is a big blow, having on numerous occasions throughout the year expressed his eagerness "to represent the United States.''

Adam Scott, Louis Oosthuizen, Charl Schwartzel, Graeme McDowell and Vijay Singh are other major championship winners who are not going.

"It's been a set of unique circumstances that has developed over the past year or so with respect to the decisions that players have made to decide to participate or not to participate,'' said IGF vice president Ty Votaw, an executive with the PGA Tour. "But in terms of our outreach, our education, our trying to get them to understand what all the issues are and what the risks and other factors may be, we think we have done everything we can to educate them in the best possible way.''

Among the other concerns has been scheduling. The men's Olympic tournament begins just four weeks from Thursday, with another major championship, the PGA, in just two weeks. The PGA Tour also scheduled an event, the John Deere Classic -- where Spieth is the defending champion -- for the same week as the Olympic event.

The following week is the Wyndham Championship, the last event of the regular season, followed by the FedEx Cup playoff events. For Americans and Europeans, there is also a Ryder Cup.

"Personally, I don't like it,'' defending Open champion Zach Johnson said of the schedule. "The fact that it [Olympics] jumbles everything together. There's not many positives for us. It's really hard to navigate when you have major after major after major and very little time off ... And no offense to the Olympics, but I'd rather be on the Ryder Cup team, personally.''

Golf is set to be part of the Games in 2020 in Tokyo, but sometime next year the International Olympic Committee will vote to decide its standing -- as it will with all sports -- for 2024.

"I think it's worth remembering the tennis experience when they came back into the Olympics in 1988,'' Dawson said. "They had quite a lot of difficulty attracting the top players to play, and just look at it now in the intervening years; tennis has become a very significant Olympic sport and very well-supported by the top players. I think golf will take a little bit of time as well. But I don't think it will take that long.''