The second-row forward smashed into Barclay above shoulder height while the Scot was crouched at a ruck position in the 17th minute of the match.
The Television Match Official did not review the incident although many expert observers have viewed it as a potential red-card offence from the Frenchman, whose side went on to dismantle the Scots 32-3 at the Allianze Riviera.
The citing commissioner has intervened and Gabrillagues will face a hearing in London on Tuesday.
“I haven’t seen it back yet, but I got hit straight on the head with a shoulder,” said Barclay immediately after the match in Nice late on Saturday night. “It’s just one of those things.
“But then I started to feel ill and thought I was going to be sick. But I’m fine now, it was just a nervous response. But it wasn’t a head knock, it was more a neck knock.”
Barclay only returned for his new club Edinburgh at the end of last season after a long-term ruptured Achilles injury and the 32-year-old admitted the result and performance at the weekend was not the best return to international colours since March 2018, when he was Scotland captain.
“Yeah, it wasn’t very good,” said the 72-capped veteran of a hugely disappointing start to the four-match World Cup warm-up series.
“It looks like we didn’t play very well. It was one of those games where it’s very hard to work out what the main problem was until you really go over the footage.
“I felt like we were too tight in defence and not getting around the corner, but is there a reason for that?
“It felt like we were all at sea and trying to find a solution. But we didn’t attack very well with the ball and we didn’t defend very well so it was a bit of a wake-up call.”
Barclay is too long in the tooth in his rugby career to be pressing the panic button just yet, though, with three more games against France at home and Georgia away and home before the flight to Japan.
“It’s better for it to happen now, and that’s probably how we’ll look back on it,” said the former Glasgow and Scarlets man. “But there will be a lot of lessons – it’s a cliché that you learn more from defeats, but it’s also true.
“In pre-season you’re in this little bubble and you think you’re going great but everyone is thinking that because they haven’t played a game yet. Once you’ve played a game you figure out that there are areas that you need to spend more time on than others, and Saturday was a bit of a wake-up call for us.
“We’ve worked extremely hard over the summer, but this game has identified that there are still some areas to work on.”
In the immediate pain of defeat, Barclay wasn’t quite sure what the plan would be for Saturday’s rematch with the French at BT Murrayfield.
“It’s hard to know where to start because we didn’t score a try and we conceded a lot of tries [five], so both sides of the ball were not good enough,” he said.
“For me it was quite interesting that the conditions were probably quite similar to those we’re going to play in in Japan – extremely slippy in both attack and defence, which they seemed to be more adapted to than us. We’ll have to look at our defence and see how we slow ball down more because there was zero flow to our attack and our defence.”
Assuming Barclay is fit after the weekend, of which there may be an update from the Scotland camp today, as a senior player he is desperate to get back on the field and help make amends, but knows selection for these matches must come with an element of experimentation.
“It’s a big squad, and while personally I’d love to play next week to get a few games, there are a lot of guys who have worked hard in pre-season, and after you’ve been beaten like that you can’t expect to play,” he said.
“We’ll look at that as a blip in pre-season, but if that happens twice in a row you’re not thinking the same thing. If that happens next week then we’ll be wondering what the hell’s going on.
“But Gregor will have ideas of how to change things. The guys in there will all want to make amends, and you’re playing for Scotland so you want to win. We didn’t do very well, but the guys in the squad who didn’t play will feel this defeat every bit as much as those who did play, and they’ll want to respond too.”
Barclay doesn’t need reminding that a man-of-the-match display in the warm-up series four years ago wasn’t enough to get into Vern Cotter’s England 2015 squad.
“It’s been a driver for me for many years now. I’m desperate to go to Japan,” he stressed. “So my ideal scenario would have been to come here [to Nice] and have a great game and for us to win, and for us to be drinking Champagne tonight, but it’s not quite worked out like that.
“But that’s the way the cookie crumbles sometimes. You’ve got to get yourself up, dust yourself down and go again.
“We’ve got three games to get into a groove, learn how we’re going to play, and get a bit of confidence and flow to our game before we can even begin to think about the World Cup. We very much have to think about how we can turn things around and learn the lessons because the World Cup games come thick and fast so you have to learn lessons pretty quickly.”