The first hint came when Alan Solomons, Edinburgh's head coach, held back five of his main international players from last night's RaboDirect PRO12 match, while hinting that both the props on the bench were expected to fill a similar role for the national side next week. So, seven of the 23 down; 16 to go.
The picture became even clearer when Gregor Townsend named his Glasgow team to face Connacht in Galway this evening with nine players held back by the national selectors. That answers further questions, including who Johnson will play at fly-half: Ruaridh Jackson and who will act as understudy to Greig Laidlaw at scrum-half: Henry Pyrgos.
Townsend insists the days when international demands would destroy any hope of victory for the teams losing players. "Last season we won every game during the Six Nations, when we were affected the most," said the Glasgow head coach. "We have a strong squad, which is something we have talked about; we need competition for places to get the best team when everyone is available but also when players are not available, you give other players opportunities to start."
In fact, Scotland's requirements have probably forced Townsend to make rather fewer changes than he has often done when he has had a full squad to pick from. There are only seven new players in the starting XV compared to the one that began against Munster last week, with the most interesting being his decision to experiment by playing Niko Matawalu, the Fijian scrum-half, at full-back.
It is a position he has filled for his national side but not for Glasgow and, after a difficult week - he had an accusation of biting an opponent hanging over head for five days before being cleared - it is asking a lot of him to play there.
Worse still, he will be up against Dan Parks, the former Glasgow favourite now at Connacht, and, with the weather forecast set for foul, Matawalu can expect to have his positional play tested to the full. One reason for putting him there is that Sean Maitland, Tommy Seymour and Sean Lamont are all in the Scotland camp and expected to form the back three against Japan. "It was something I had looked at at the start of the season," Townsend said. "When I watched him play for Fiji in the summer he played two Tests at full-back and one at scrum-half, and was outstanding at full-back.
"He ran really well at training and it is an exciting back three. We needed experience in those positions and Niko, DTH [van der Merwe, the left wing] and Byron [McGuigan, the right wing] have been on form. We can expect a few kicks to them, so we will have to deal with them well."
It is all change in the front row with both Ryan Grant and Pat MacArthur away with Scotland, giving Dougie Hall a start as he plays his 150th league game in a career that started at Edinburgh before his move west.
The make-up of the second row, hints the injury that forced Jim Hamilton, the Montpellier lock, to miss training this week is a worry for the national selectors who have held back both Al Kellock and Tim Swinson to compete for places alongside Richie Gray.
"We have had 19 players away this week on training camps with Scotland and Fiji so you have to adjust," Townsend said. "We coped with it well last season. It is about getting the focus, getting the team together and getting the session right when you do have them all together. The goal is winning the game at the weekend.
"Players have to be managed. It is very difficult to play at the highest level for more than five games in a row. When you have three Tests to come, playing two games before that would make it very hard for them to play at their best at Test level."
For all that, tonight's game is a huge one for Glasgow, who have won only four of the 11 games they have played at Connacht's Sportsground. With their unbeaten start to their league season ended last week, a second defeat would rip all the momentum from their campaign.