Gregor, deputising for the Scotland-tied Dan Parks, scored 21 of Glasgow’s points – including a crucial converted try and two penalties just after the break – to allow them hang on for a 26-20 win over the Celtic League leaders at Thomond Park.

Having scored three first-half tries through captain Anthony Foley, Stephen Keogh and Anthony Horgan, Munster were left shell-shocked when Gregor single-handedly doubled Glasgow’s first half tally for a 26-17 lead, 11 minutes into the second half.

Laying siege to the Glasgow line, Munster were left frustrated as a sequence of knock-ons and loose passes prevented them for getting a fourth try – a score that would certainly have won it for them late on, after fly half Mossie Lawlor had closed the gap to six with a 72nd-minute penalty.

Having earned their first ever win (32-10) over Munster at Hughenden in September, Hugh Campbell’s men travelled south with a degree of confidence, helped by the presence of six members of the Scotland 6 Nations squad in their match-day 22.

Munster began in fine style when inspirational number eight Foley followed up on flanker Kogh’s surge from a ruck to score in the left corner after only three minutes. Lawlor missed the conversion.

Munster’s lead was short-lived – just four minutes later, Gregor combined with his captain Jon Petrie to put scrum half Sam Pinder over behind the posts for a converted try.

Gregor added a penalty on 13 minutes, but Munster bullied their way back in for a 17-13 lead at the interval.

Keogh lunged over from a close range ruck for the hosts’ second try on 31 minutes and while Gregor kicked his second penalty, Barry Murphy and John Kelly made the hard yards for winger Horgan to cross the whitewash in injury-time.

Gregor, though, left Munster punch-drunk after the restart when he sandwiched a 47th-minute try, set up by new centre Spencer Davey, in between two penalties to establish a nine-point buffer for Campbell’s men.

Munster dug deep to try and muster a comeback but the Glasgow defence shut up shop for the closing half-hour.

The visitors lost winger Mike Roberts to the sin-bin for a high tackle, five minutes from time, but the Scots hung on for only their second win in eight games.