Former Ireland wing Tommy Bowe says Jack Crowley has moved ahead of Ross Byrne in Ireland's fly-half pecking order behind captain Johnny Sexton.
Bowe feels their contrasting fortunes at club level have pushed Munster out-half Crowley ahead of Leinster's Byrne.
Crowley helped Munster win the United Rugby Championship title in May.
While the 23-year-old was superb in the URC final win over the Stormers in Cape Town, Byrne and Leinster suffered heartache in the Heineken Champions Cup final as they let slip a lead to lose 27-26 to La Rochelle.
Bowe, who played for Ireland at the 2011 and 2015 World Cups, told the Rugby Union Weekly podcast: "I would have thought going into this competition that Ross Byrne, who is the number two at Leinster, would have been a like-for-like replacement for Johnny Sexton. He would have sat on the bench.
"I wonder how much the impact of the Champions Cup final has had on him because he was the out-half pulling the strings against La Rochelle. Leinster were all over them at stages, he had the opportunity to take a drop-goal but decided to keep on playing and didn't take it.
"Leinster lost by a point and they're the crucial minutes that mean a huge amount going into a World Cup. Crowley, on the other hand, dropped a goal to beat the Stormers and win Munster's first trophy in 10 years.
"So I think the pecking order has changed. Byrne would have been second choice to Sexton in the Six Nations but Crowley has now taken that spot."
Having served his three-match suspension for misconduct towards match officials following Leinster's loss to La Rochelle, Sexton will be available for Ireland's World Cup opener against Romania in Bordeaux on 9 September.
However, while the captain's return will be a big boost, Bowe feels scrum-half Jamison Gibson-Park is more important than the out-half in head coach Andy Farrell's system.
The former British and Irish Lions back said: "Johnny Sexton pulls all the strings but if you talk about Andy Farrell and the tempo this Ireland team are playing at, Conor Murray got man of the match at the weekend [against Samoa], he was exceptional but he doesn't play at the same level of tempo as Gibson-Park.
"Going against the bigger, faster teams, Gibson-Park is really important to this Ireland team."
'Ridiculous to have top five teams on same side of the draw'
Bowe feels that while Ireland suffered a few "blips" in the build-up to the 2019 tournament in Japan, Farrell's side have "done everything right" as they prepare to open their campaign as the world's number one ranked team.
Ireland have never progressed beyond the quarter-finals of the World Cup and while they look well-equipped to break new ground, they face a tough route with South Africa and Scotland alongside them in Pool B and the likelihood of France or New Zealand in the last eight if they reach that stage.
Bowe says the fact that the top five teams in the world - Ireland, South Africa, France, New Zealand and Scotland - are all on the same side of the draw is a "ridiculous".
"It will make the pool stages very interesting, but it is very frustrating to think that of the top five teams, two will make it to the semi-finals.
"It does rankle a little bit because Ireland have done everything right going into this World Cup.
"Yes they could get to the quarter and semi-finals, but I think in terms of the governance for a World Cup competition, to think they've made the draw three years out from it, it doesn't really paint rugby in a great light in that sense."