Taking one touch to get the ball out in front of him, Rashford unleashed a dipping, swerving shot which rocketed into the top corner over the stranded Keylor Navas.
But while that competition may have come too soon for the young players, it was a massively important learning curve for the group, who have now been together long enough to suggest that Russian Federation may just well be where England finally shines following an impressive qualifying campaign.
At the back too, players are forcing Southgate to think again about his starting line-up.The wing-backs in particular were excellent against Costa Rica, with Danny Rose and debutant Trent Alexander-Arnold showing that they've got the defensive nous and attacking flair to make an impact in Russian Federation.
Stones started in the middle of Gareth Southgate's preferred back three between Harry Maguire and Phil Jones and was only troubled once in an assured display before being replaced by Gary Cahill in the 65th minute.
Danny Welbeck has taken a thinly-veiled swipe at Manchester United boss Jose Mourinho by claiming that Marcus Rashford is free to "express himself" when on worldwide duty with England. "I said to the team that I expect to see mistakes because otherwise we're not trying things, and with attacking players in particular". Given the number one shirt after starting against Nigeria, the three-cap keeper looks a bold selection.
"He had a hard end to the season having to play on his own as a number nine at times".
"It gives you that freedom to go out and play on the pitch".
Real Madrid goalkeeper Navas was completely caught out moments later, though, as Rashford unleashed a powerful drive from 25 yards that dipped perfectly over him and into the top corner for his third global goal. "He is still filling out - we sometimes forget how old he is".
It would be a big risk to play Rashford.
"A little bit different in that obviously (there was) a slightly different profile of players, so maybe we didn't get as many men in the box at times".
"I don't see why it should be overly mental". It wasn't the first team against Nigeria and second team today.
Rashford said after the game he needed to improve as he gets ready to represent his country at a major tournament for the second time - he came on briefly against Iceland at Euro 2016 as the Three Lions were eliminated. "This year, I feel in better condition and that's good".