Shane Ryan, 22, has the 25th fastest time in the world this year in his signature event, the 100m backstroke. But with five swimmers ahead of him on the US team, it looked like he might never have the opportunity to compete at an Olympic Games as an American.

Luckily, Ryan, from Haverford, PA, holds dual American and Irish citizenship and last year decided to switch allegiances to the Irish team, with hopes of being allowed to compete for the most coveted of sporting achievements: an Olympic gold medal.

The 22-year-old swimmer was criticized for his decision to relocate to Ireland, but for the Penn State student, who played GAA in his youth and who will return to school next year to complete his final year, the move was an easy one. His father had moved to the US from Ireland to play GAA in his youth and remained in the country to raise a proud Irish-American family.

For the past year he has lived in Ireland, interning with the Football Association of Ireland, training with Swim Ireland, and reconnecting with family he met across many summer vacations.

“I was happy just being there, even if I didn’t qualify for the Olympics,” he told the Delaware County News Network.

“It was great. I got to connect in a different way than by the phone or Skype. I got to be there, to do things with them and to get to know who they really were.”

'It's my decision' - Irish swimmer Shane Ryan defiant amid allegiance switch criticism:

— (@The42_ie) July 23, 2016

In his first Olympics, Ryan will compete along with the two other Irish swimmers who have made the grade – Fiona Doyle and Nicholas Quinn. Ryan's first race is on Sunday, August 7 at the Olympic Aquatics Center.

The Irish-American swimmer will not be the only swim competitor in Brazil with a history of embracing their Irish heritage. Unlike Ryan, however, Katie Ledecky will proudly wear red, white and blue. Set to be a star of this year's Games, Ledecky (pictured above) looks to follow up on her shock gold medal in London when she was just 15 years old.

In April of this year the Seattle Seahawks' draft pick Alex Collins revealed how he used Irish dance to help him on the football field. That tradition may also have influenced the 19-year-old Ledecky, who took part in Irish dance classes when she was younger.

Read more: NFL top prospect uses Irish dance to help his moves

Ledecky, who was born on St. Patrick’s Day, has quickly taken over the swim circuit since the 2012 Games. In addition to her Olympic gold medal, she is a nine times world champion, has already broken 11 world records in her career and was the youngest person on Time’s Time 100 Most Influential People list in 2016.

The clash of loyalty between different countries is one thing when you have to make a decision for yourself, but few would envy the fate of one Co. Antrim father who could possibly see his sons face off against each other in the men’s field hockey competition.

Athletes born in Northern Ireland can choose whether they compete for Britain or Ireland. (Confused? The video below from Irish comedians Foil, Arms and Hog may help to clear things up.)

Paul and Mark Gleghorne have decided to play for Ireland and Great Britain respectively, although Mark originally represented Ireland until he switched allegiance in 2011.

The brothers have competed against each other internationally before, but that won’t make it any easier if they find themselves battling it out in Brazil.

"I find playing against Paul very weird. It’s not something that is particularly nice because Paul and I are close,” Mark told the Belfast Telegraph. “We talk a lot and we’ve grown up together so that’s why it’s a bit strange."

The Irish men’s field hockey team will kick off their campaign this Saturday morning at 3pm against India, the first time Team Ireland has been represented in this sport for over a hundred years. They face a steep challenge as the 12-team competition has six teams who have already taken home the gold in previous Games.

Honoured to have been selected to represent @IreMenHockey at the Rio 2016 Olympics! Thank you to all who have helped

— Paul Gleghorne (@PaulGleghorne) July 11, 2016

Honoured to have received my 100th cap for @_GBHockey @EnglandHockey last week. Thanks to everyone for the messages!

— Mark Gleghorne (@MarkGleghorne) July 18, 2016

Before the sports can properly begin, however, there is today's opening ceremony, during which Team Ireland and their flag bearer Paddy Barnes will hope to put the country’s own controversy of the last few days behind them.

Who are all these other flag bearers? @SkySportsNewsHQ #rio2016

— Paddy Barnes (@paddyb_ireland) August 3, 2016

Barnes is hoping to become the first Irish athlete to win a medal at three consecutive Olympic Games, having won bronzes in 2008 and 2012. The boxer was the obvious choice to be the Irish flag bearer, but Thursday's report that fellow boxer Michael O’Reilly has failed a drug test has shaken the boxing team. As of last night, however, O'Reilly appeared to still be fighting in the Games. 

Box on the 12th in the last 16 against the winner of Mexico or Iraq.....

— Michael O Reilly (@michaeloreillyb) August 4, 2016

Prior to the doping reports, the team's preparations had been going well and the team was relaxed and ready. The team’s Chef de Mission Kevin Kilty told RTÉ News that there was a friendly atmosphere and that Team Ireland had already made sure to leave their mark on the Olympic Village.

“We really put a special effort to branding up the building,” he said.

“From the front of the building we have the tricolour on all of our balconies and you can see it from anywhere in the village.”

Team Ireland may be missing Rory McIlroy, who excused himself from the competition due to the risk posed by the Zika virus, but they have plenty of other talent among their 77 competitors across 14 sports, including Irish golfing legend Pádraig Harrington and Irish national treasure, boxer Katie Taylor.

Taylor sent Irish sports commentators into tears when she took home the only Irish gold medal from London in 2012 and she returns to defend her title this year. She will start her own campaign on Monday, August 15.

Everybody is looking forward to hearing a reaction like this again. (Tears translate the same in English and Irish):

Team Ireland has competed in the summer Olympic Games since 1924, when it sent 44 athletes. There were no Irish medals that year, but two tournaments later, despite having just eight athletes competing, the Irish team was ranked 16th with two gold medals.

The London games in 2012 were to be the best Irish performance so far, with one gold, one silver and four bronzes.

Here’s hoping Team Ireland can do one better in Rio!

You can follow all the action of the Irish Olympic team on their Twitter page here.

Read more: Ireland’s original Olympics - the Lughnasa games (VIDEOS)