Johnny Sexton: It's a big call for Simon Zebo to potentially sacrifice a World Cup
The Munster winger is following the route Sexton took in 2013 in signing for Parisian club Racing 92, but the 32-year-old Leinster star believes the circumstances are very different.
The out-half was allowed to continue playing for Ireland during his two seasons in France, winning the 2014 and 2015 Six Nations and admits it was difficult to marry the two commitments.
Since he returned to play for Leinster after the 2015 World Cup, Ireland coach Joe Schmidt has not called on any overseas based players.
While the IRFU do not have a stated policy on the issue, selection calls have always gone the way of the home-based players.
Once he departs for Paris at the end of the season, the Corkman is unlikely to be selected for the national team and is likely to be out of contention for the 2019 World Cup.
"When I went it was a little bit different because there were no rules in place about not being able to play international rugby, so the challenge for me at the time was trying to marry the two and it was very difficult," Sexton said.
"I found it very tough, to miss out on camps, to miss out on a week's preparation in the Six Nations even though we won the two Six Nations while I was away. It's not ideal.
"You're well looked after here, you're rested at different times so you can peak for the big competitions with Ireland.
That's what I struggled with. It's obviously a big call for him to sacrifice a World Cup potentially and what else can happen before that if we achieve what we want to achieve over the next few years it will be tough for him.
"But I'm sure he's weighed all that up.
"And again, everyone's circumstances are different. The decisions I made at the time maybe are totally different to what Simon is going through.
"I'm sure it was very tough either way, because he's definitely Munster through and through. It would be good to see him back here in a couple of years - I don't know how long he's signed for."
Sexton believes Racing has become a very different club to the one he joined five seasons ago.
"It's probably a very different place," he said.
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"I just saw on social media that their new stadium looks like it's opening up soon. Straight away, it's going to be much better.
"Look, it's going to be a big challenge for him but it's probably something he wants to do. It's a big loss for Munster and Ireland.
"He's a big figure down there (in Munster), a big player for them, I'm sure they're all gutted he's gone. Everyone has got different circumstances and I wish him all the best."
Zebo was not always a first-choice player for Ireland coach Joe Schmidt, but over the course of the past season he has been a regular starter.
But, while he admitted the full-back is a loss to the team, Sexton believes they can cope and others will step into the breach.
"Him and Joe seemed to always get on well, once Simon has been doing what Joe wanted of him he's got picked because he's so talented and so good," he said at an event to promote Aer Lingus today.
"From that point of view, I think personally Simon is only going to get better. It will be a loss of course for Munster and Ireland but we've got so much good talent in the back three coming through.
"Not that it won't be a loss, I'm sure it will be harshly felt in Munster."