Kangaroos winger Josh Mansour has been ruled out of the remainder of the Four Nations with a knee injury.

Josh Mansour has capped an incredible 12-month journey, with the Panthers winger named in the Kangaroos squad as an injury replacement for Darius Boyd less than a year since he tore his ACL while on Four Nations duty.

The 27-year-old said he felt sorry for the Broncos fullback and could empathise with his situation given he missed the bulk of last year's post-season tournament in the UK as well as a large chunk of the 2017 NRL Telstra Premiership campaign due to injury.  

Having missed out when the original squad was named on Tuesday, it's been a whirlwind 48 hours for Mansour who attended Penrith's Merv Cartwright Medal awards night on Wednesday and then took his pregnant wife to the doctor for a check-up on Thursday morning before he got the good news.   

"It's been a crazy day, I'm not going to lie," Mansour said at the team hotel on Thursday. 

"I was actually at the obstetrician with my wife before this and then I got the call, so I can't wipe the smile off my face. I'm very excited and grateful to be back in the squad; it's been a crazy 12 months. 

"I didn't know how to handle it. I broke the news to my wife and we were both very happy. Obviously we're trying to plan what's going to happen around the birth in four weeks' time. These opportunities don't come around very often so I'm very happy to be back."

With Australia set to open the World Cup against England on October 27 - and with the Kangaroos drawn to play France in Canberra on November 3 – Mansour revealed he would be willing to miss either game in order to be with his wife should she go into labour.

It's a small sacrifice for the powerhouse winger who says his wife's support helped him through the tough times as he recovered from the devastating knee injury.  

"There's no plan at the moment. The baby is due on the 2nd [of November] and whatever happens around that we'll just have to wait and see. I think we play in Melbourne against England on the 27th of October and after that we'll be in Sydney so that's alright," he said.

"She sacrificed a lot in my football career so I think I'll be there for her. She's really supported me through these 12 months, she's been amazing and I'm very lucky to have her by my side. I'm definitely going to be with her and hopefully it can be a good day for us."

While Boyd (hamstring) is the hard-luck story of the World Cup so far, Mansour's return from injury has been nothing short of inspirational. 

Having grabbed a double in Australia's opening Four Nations win over Scotland, the winger was struck down in a skills game at the end of a training session, ruling him out of the tournament.

It was a cruel blow for a player who had only just reclaimed his Kangaroos jersey after a two-year hiatus, with the injury sidelining him until Penrith's Round 13 win over the Bulldogs. 

Mansour scored an emotional try in his return game and was a key reason why the Panthers overcame a horrible start to the year to reach the second week of the finals series. 

He is now fully fit and ready to make the most of this golden opportunity, although he knows nothing is guaranteed with plenty of competition for the two wing spots. 

"The first couple of games when I was playing, it did [play on my mind], but we have a great medical team that have really helped me along the way," he said. 

"Everyone supported me to get back on my feet and I'm really confident in myself and I've got no worries at all. 

"It's very rewarding to be back here. These opportunities don't come around very often and to play in a World Cup on home soil is very exciting."

Had he not been selected in Meninga's squad, Mansour would have been one of the first players picked for Lebanon.

However, Mansour revealed he would have skipped the World Cup instead to spend time with his family after a hectic 12-month rollercoaster of emotions.  

"I was tossing and turning on what I was going to do. It was a very hard decision but I ended up deciding that I was going to put all my time and effort into my wife," he said. 

"It's been a very taxing year on my mind and my body so I thought it would have been a good opportunity to spend some time with my wife. Not having a honeymoon with her last year hurt, and she's sacrificed a lot, so I would have owed that to her."