"We have worked to make them compatible and Paulo has improved a lot from this point of view," the former Chile boss explained. "But I still have to wait before playing them together. The right time has not yet come."
What about now, though?
Despite the Albiceleste's glaring problems in attack, Dybala has featured just once so far, as a late replacement against the Croats. Consequently, there have been calls back home for him to start against the Super Eagles.
However, while the under-fire Sampaoli once again plans several panicked changes in personnel in another desperate bid to belatedly bring some balance and cohesion to his side, Dybala is unlikely to be one of them.
Judging by the latest leaks coming out of the Argentine camp, Angel Di Maria will be recalled on the left flank, while Gonzalo Higuain could be preferred to Sergio Aguero to spearhead an Albiceleste attacking triumvirate that will feature Messi on the right-hand side.
That means no room for Dybala, which has essentially been the story of his international career to date.
Despite being regarded as one of the best attacking talents in world football, the 24-year-old Juventus ace has started just seven times for his country, with his six other appearances coming as a replacement.
There have been no goals and just one assist – remarkably poor numbers all round for a player who has essentially managed a goal every two games in Serie A (52 in 98 appearances) since joining Juventus for an initial €32 million in 2015.
However, there were two issues with that notion. Firstly, Dybala is not yet on the same level as Messi – and probably never will be. Secondly, he doesn't seem capable of playing alongside his fellow left-footer either.
Indeed, only last year Dybala admitted that "it is not easy to play with Messi because we play in the same way".
There were those that inexplicably interpreted that observation as a criticism of his captain but Messi knew exactly where his young team-mate was coming from.
"I spoke to Paulo about [those comments], and what he said is the truth," he told FoxSports.
"At Juventus, he plays just like me; we look for the same spaces. Alongside me in the national team, he had to play more on the left, and maybe he's not so used to that.
"It is harder for us to play on the left. I rarely venture down the left-hand side. On the right, we can cut inside and we have the whole pitch in front of us.
"The truth is that I understood exactly what he meant, so there was nothing that needed clarifying."
However, we could do with clarification from Sampaoli as to why he appeared to give up on trying to find a solution. After all, he started the pair alongside one another in a 3-4-2-1 formation in his first game in charge, a 1-0 win over Brazil last June.
But after being underwhelmed by the pair in the qualifier draws with Uruguay and Venezuela, Sampaoli ditched the attacking midfield tandem - and Messi and Dybala haven't started alongside one another since.
As Argentina's qualification hopes began to fade, Sampaoli stated before the decisive double header against Peru and Ecuador that he no longer had time work out how to include Dybala in his starting line-up, so he left him on the bench for both games.
By March of this year, it seemed he 'La Joya' wouldn't even be on the plane to Russia. "It will be hard for Dybala to get used to our style," he said after leaving the former Palermo forward out of his squad for the friendlies against Italy and Spain.
"We couldn't improve his performances and we have to evaluate if the current players are better than Paulo or if we've to keep working with Paulo to improve his performance."
In the end, Sampaoli decided to take Dybala to the World Cup but he clearly remains utterly unsure of how best to use him.
But then again, that is hardly surprising, given Sampaoli does not need to know his best team whatsoever. He has been at helm for 13 matches and hasn't once picked the same side.
There has been no consistency in his selection process at all and Dybala is just one of a number of victims of this maddeningly muddled thinking.
The 24-year-old reiterated last week that he is not looking to take Messi's position, but flourish alongside him.
"Messi does not have any substitute here, in Barcelona or anywhere in the world, so obviously I think we should and could work together," he told reporters. "We just need to figure out how I would fit on the team."
It seems too late for that now, though. Dybala has long been willing to make it work. Sampaoli has been unable to make it happen.