Rob Holding was in the stands at the Emirates in January, watching Arsenal's match against Chelsea with his girlfriend, when Hector Bellerin twisted his knee and crumpled to the turf. The early signs were bad, and Holding's phone lit up as friends sent him videos of what had happened.
Only a few weeks earlier, Holding had undergone surgery on his own ruptured knee ligament.
As he watched the close-up replays, and as it became clear Bellerin was suffering from the same season-ending agony, Holding began to cry. "It was so raw for me," he says. "It hit a spot and I got a bit emotional with it."
The nature of their respective injuries last season, so similar and so close together, allowed Holding and Bellerin to share in each other's journey back to fitness. There were "dark times" in the recovery, Holding says, but a strong connection was formed.
It was no surprise, then, that Holding and Bellerin shared a hug on Tuesday night, when both made their first-team comebacks against Nottingham Forest.
Holding not only played the full match, but also scored with a second-half header. "You could not have written it any better," he says.
In his own words, it will all come full circle tonight as he returns to Old Trafford where his left knee buckled last December. "It will be brilliant to just walk back to the spot that it happened and take it in," he says. "You could say it is a bit of closure for it to happen there and then the first [league] game is back there."
Plenty of Arsenal fans will be hoping that Holding is deemed ready to start the match. In many ways his reputation has been strengthened by his absence, with Arsenal remaining so defensively fragile without him and Bellerin. Unai Emery's side did not lose any of the 16 games Holding played last season and, along with Bellerin and new signing Kieran Tierney, he forms part of what could be a new defensive core.
Tierney, the £25m arrival from Celtic, also made his first appearance of the season on Tuesday, when he was exceptional. He too has forged a close connection with Bellerin - the "full-back union", they call it.
They are similar ages, speak the same language and are close friends off the pitch. Factor in Calum Chambers, and there is an encouraging tightness to the long-term defensive unit, which will be further strengthened by the arrival of teenage centre-back William Saliba next summer.
There are even some similarities to the great back four of Lee Dixon, Tony Adams, Steve Bould and Nigel Winterburn that was built under George Graham.
The average age of those players when they first became a unit was 23, the same as Tierney, Holding and Bellerin's average age now.
Graham's side were formed as the club pivoted towards young players and discarded more senior figures in the late Eighties. The same has happened this summer, when 11 senior players left Emery's Arsenal as part of a major overhaul.
"Graham was coming into a team with fairly established players but within a year he got rid of the likes of Graham Rix, Steve Williams and Charlie Nicholas," said Winterburn.
"George knew the way he wanted to play and what he wanted to achieve. It looked to me that he felt it would be too difficult with the senior players there. So he decided to move them on and bring players in that he could work with who were younger and hungrier."
This is not to say Arsenal's new cohort will prove even half as successful, but the sense is a new generation is coming through, exciting the supporters. "I was speaking with Kieran," says Holding. "We were saying there is actually a bit of pressure on me, Hector and him. It is a healthy pressure. It is pushing everyone to be better."