Four minutes into the 1-1 draw with Coventry City, Glenn Loovens picked up an injury.
Jack Ross opted against a like-for-like replacement, bringing on Adam Matthews.
Matthews had been one of a few who lost his place after defeat at Burton Albion but he kept his place after this return and from there he has started every league game.
Not only that, he has excelled in what looked like becoming a problem position for Sunderland and established himself as a key figure in a defence that has delivered with impressive consistency.
A switch from the lopsided 3-5-2 to a more conventional back four has certainly helped, but Matthews has also begun to hit the levels that marked him out as one of the most impressive talents north of the border.
Ross admits he laid down a challenge for the 26-year-old and has been thrilled with his response.
“I like him, I knew him from Celtic and what I would say is that the last couple of months have shown what he is as a player,” Ross said.
“I think he’s getting back to the player that I believe he should be.
“I had a good couple of conversations with him and credit to him that he’s wanted to try and do that.
“It was slightly unfair on him earlier in the season because we went to the back three and he was slightly out of position,” Ross added.
“Thereafter he had a couple of games where I think, by his own admission, he wasn’t quite at it.
“We left him out and had some chats with him.
“You’ve always got to think about the player’s point of view.
“It’s easy to think, ‘I’ve dropped him, he’ll just bounce back’.
“It was more about where he’s at with his age, what he’s achieved in his career to date .
“He’s played international football with Wales, he’s played in the Champions League with Celtic. Just encouraging him, saying, ‘make sure you don’t think that’s it.’
“He’s still young,” Ross added.
“I like him from an individual point of view and I enjoy speaking to him about his game, I wouldn’t say it was make or break but it was interesting to see how he would take that conversation and to his credit, he’s really kicked on from them.
“And I think he’ll get better as the season goes on, I think he’s got more.
“He’s been a good player for us in the last couple of months.”
Ross was making his first steps in coaching as Matthews impressed at Celtic.
The Welshman won six major honours during his time there, famously marking Lionel Messi during an iconic Champions League win.
He was a player Ross marked out as a potential asset when he first took the job and though it has taken a while for him to hit his stride, the Black Cats boss hopes he can now play a vital part in the push for promotion.
“On paper, at the beginning of the season he was one where I’m thinking, ‘what a good full-back I’ve got’, Ross said.
“His performances for Celtic were very good and hence the reason why Sunderland were interested.
“He’s quick, powerful, he can defend, he’s got really good attributes.
“I would say from day one, he’s been really good for me in training, it’s just that I wanted to see it all the time in games and over the last seven or eight he’s shown that.
“I think he’s in a good place, we’ve spent some time with him this week individually looking at some things, he wants to keep getting better,” Ross added.
“That’s the kind of thing people don’t see at times, him wanting to keep improving.
“I’m glad he does, because like I say, I didn’t want him to think in his mid-twenties, ‘I’ve done all I can’.
“Because he has done a lot. But the next part of his career he can replicate that and achieve more.”
Matthews sees his current deal expire at the end of the season and in the matchday programme last week, he admitted that he would like to extend his current stay.
The situation is complicated by the fact that he is one of the group of players whose wages did not take a further cut following relegation from the Championship.
Ross admits that is likely to mean any talks would have to be on hold as a result.
“Adam falls into a category of players [who’ve dropped from the Premier League].
“If we’re in the Championship next season then it makes all of these conversations easier.
“You can’t predict with that certainty at the moment so there is that little bit of uncertainty about how we can move forward and about a player can progress their career as well.”
In the meantime, he has the chance to add a seventh honour to that tally.