On his return home, Grant got a bit of a rest but come the second game of the season both he and Stuart Hogg, who was also among the Lions, is being thrown back into the action with the added complication of playing a position which changed radically under new rules.
Grant is one of eight players brought into the Glasgow side for their first start this campaign and is raring to go as his side take on one of their toughest tests, facing Ulster in their first competitive match inside the rebuilt Ravenhill stadium.
When Grant last played, the scrum was determined by the way in which the two front rows came together - what was known infamously as the "hit". Now it involves a more gentle collision and a test of strength similar to that in a wrestling match. Grant cannot wait to get his first taste of it.
"The training sessions have shown it is still very full-on," he said. "The hit has been taken out of it, which takes a bit of the uncertainty away, but judging from the way the boys played last Friday in very wet conditions, the scrum did well. It stayed up a lot, was a lot more stable and we got a lot of good ball from it. On any other night, in those conditions, you would expect a lot of scrums to go down so I am going to stay positive and see how it goes in the game."
It is still far too early in the season to consider this a make-or-break match for Glasgow but, alongside the home game against Leinster seven days later, this fixture will establish the strength of their title challenge. Not only are the two Irish provinces the sides which fought out last year's RaboDirect Pro12 final, but Leinster won all three of their meetings with Glasgow last season and Ulster won three of the four encounters with the Scots in the league and Heineken Cup. A win at a ground where no Scottish side has won since 2009 would be a powerful statement of intent.
Ulster are not as strong as they can be either. Unlike Glasgow, they are still resting their Lions, while Ruan Pienaar, the South African scrum-half, is still away on international duty and Andrew Trimble, the Ireland wing, yesterday became the latest to succumb to injury.
Glasgow are closer to full strength. Ruaridh Jackson is back at fly-half after helping change the pattern of the game when he came off in last week's win over Cardiff Blues. Interestingly, though, Gregor Townsend, the Glasgow head coach, has elected to stick an extra forward on the bench and use Hogg to cover at fly-half.
In the end, Hogg played more at No.10 than No.15 for the Lions in Australia, but Townsend is clear that he sees the player more as a full-back who can fill in other roles than as a long-term option for the pivot role. "The make up of our bench this week meant that we decided to put an extra forward in the set up in the knowledge that Stuart has played 10 and could step up there," said Townsend.
Part of the reason for that extra forward is that he does not have an out-and out lock replacement, with Al Kellock having injured an ankle last week - although scans have suggested that his ligament damage will only keep him out for a matter of a weeks not months - and Tom Ryder having picked up a head knock. James Eddie and Rob Harley could cover the role but Townsend is able replace the entire back row should the need arise.
It is a gamble he has taken before but one which has also backfired spectacularly, notably away to Northampton in the Heineken Cup last season when three injuries in the backs awas a factor in allowing the English club to come from behind to win the game and set the tone for Glasgow's dreadful European campaign.
Despite that experience, Townsend is hoping negotiations to save the Heineken Cup - with English and French clubs considering breaking away -will succeed in keeping the competition going. "We are all desperately hoping as players, coaches and supporters that the European cup is in existence next year," he said. "I have played in both Super Rugby and the European Cup and I know that the nations in the Southern Hemisphere really envy our club tournament, probably because of the proximity of all the nations and the fact that it is six different countries, which makes it a really exciting, varied tournament."