The two have played in three NRL grand finals and Foran won a title with Manly in 2011. They first combined in this year's Anzac test and have now played six games together.
They also spend time together off the field and, while their relationship isn't at the level Foran enjoys with Daly Cherry-Evans at Manly, it's developing.
"It's growing each day," Foran said. "It's starting to feel like we are getting a really good understanding of one another's game. I'm really enjoying playing with him. He's got that real X-factor about him and I think it's coming along nicely."
What works is that they are different players and different personalities. Foran is a strong defender, good organiser and plays the ball at the line while Johnson combines good pace, footwork and ball skills with a decent kicking game. He's also the tournament's leading points-scorer with 62, 26 points ahead of Australia's Johnathan Thurston in second.
England will field a similar combination to New Zealand's in Sunday morning's World Cup semifinal, in fact one is strong and steady (Kevin Sinfield) and the other offers more playmaking ability (Rangi Chase).
Sinfield, though, doesn't tend to play the ball at the line as much as Foran, which is easier for defenders, and Chase is prone to errors (his seven is the fifth-equal most in the tournament). It doesn't mean they aren't a threat and the Kiwis are determined to keep them quiet.
One thing Foran and Johnson have done well so far in the World Cup is not overplay their hands, even though Foran leads the tournament in try assists with nine.
"There are so many talented players in this footy team," Foran said. "It's not a case of trying to come up with every play and every try-scoring opportunity. There are players all over the park who can score points so we just have to do our job well. If all 17 players out there do that, we give ourselves every chance."
It's doubtful the Kiwis will have Manu Vatuvei, who sat out training yesterday with a groin strain, and Jason Nightingale would come on to the wing if Vatuvei was unable to play.
Kevin Locke might have also done enough in the 40-4 win over Scotland to hold on to the No 1 jersey ahead of Josh Hoffman and he was running at fullback for most of the team's training yesterday. The team will be named tomorrow (NZT).