The Bhoys defender has been discussing his side's Europa League exit.
Defender Matthews says the Bhoys are used to a ‘British mentality,’ where tough tackling - inspired by the likes of Patrick Vieira and Roy Keane - comes to the fore.
But, while the Celtic man says there is nothing wrong with that approach, it isn’t to the liking of European referees.
Nor were the Hoops helped by another European addition: the mass surrounding of officials by opposition players.
As such, Matthews admits Celtic have gone wrong on that front in recent times and hopes Ronny Deila’s side can adapt to the situation next season.
“That’s just the British mentality. Growing up and watching Patrick Vieira and Roy Keane, we saw them going into hard tackles then just getting up. You didn’t see them surround the ref,” he said.
“Europe’s a bit different and we’ve got to learn from it. Virgil [Van Dijk] was especially unlucky with his first yellow card. In the Premiership I don’t think that’s a foul but the ref saw it differently on Thursday.
“We have to accept that now. Up until the sending-off, I thought we were controlling the game and we had a good chance - but it wasn’t to be and hopefully next season we can adapt better.”
However they tackled, Celtic acquitted themselves very well against Inter Milan, banishing some of their more forgettable European memories from earlier this season.
Now, though, their focus remains on domestic matters, with a treble still very much on the cards for Deila’s men.
Today’s Scottish Premiership clash with second-placed Aberdeen is as big as any - and there will no doubt be the odd crunching tackle in that one.