The Scotland international had just five tries in 42 appearances in European competitions prior to the opening round fixture, but notched his treble in 20 second-half minutes as the 2020 champions went top of Pool A with a dominant home victory.

Exeter only led 7-6 at the break, thanks to Stuart Hogg’s try, with Louis Forsans’ two penalties for Montpellier keeping it tight.

But Sam Simmonds and Don Armand went over in the second period alongside Gray’s hat-trick as they cruised to a bonus point win.

“I don’t know how that’s happened,” Gray laughed after a memorable Heineken Star of the Match-winning performance, which came in just his second game since returning from a shoulder injury.

“It’s good to be back. It was a tough match. You could see in the first half that Montpellier caused us a lot of problems. To be fair, we got a hard time at half-time off the coaches. It was good to be at home and get the win.”

Exeter’s win may have put them top of their pool, but Gray said they are under illusions about how hard it will be to repeat 2020’s triumph.

“We just know how tough this competition is and the quality of team Montpellier are,” he stated. “If you just look at the squad and the players they have, we knew we had to start well, especially at home.

“Every result matters and every point matters. We got a tough time at half-time and I'm just glad we got the win here.”

Next up for Exeter is a trip to Gray’s former club Glasgow Warriors on Saturday, a clash which the 27-year-old is eagerly anticipating.

“It will be a weird one obviously,” he said. “It's a club I care about a lot and a lot of people there are special people. It will be a tough game and Glasgow are going well.”

Head coach Ali Hepher told Exeter’s website: “It’s fantastic for him and it is great to have him back up and running. He has had a long time out injured and it is pleasing he has come back the way he has.

“He was in the right place, he was smart with the way he picked and when he laid off his passes, and he created a good opportunity as well with a good offload, so all round we are really pleased with Jon and we have got to keep him rolling.”

Exeter Chiefs lock Jonny Gray struggled to comprehend how he ended up with a hat-trick of tries in his side’s 42-6 Heineken Champions Cup victory over Montpellier Hérault Rugby on Saturday.