|Pro14: Glasgow Warriors v Edinburgh|
|Venue: Scotstoun Stadium, Glasgow Date: Saturday, 21 December Kick-off: 17:45 GMT|
|Coverage: Live commentary on BBC Radio Scotland, live text updates on BBC Sport Scotland website & app|
When John Barclay announced his international retirement a few weeks back, Hamish Watson dug out a picture from 2018 and sent it to Ryan Wilson.
It was a celebratory shot from the last Calcutta Cup victory at Murrayfield, a happy image of the men who played in Scotland's back-row that day - Watson, Wilson, Barclay and Dave Denton.
"Two down, two to go," wrote Watson in his message to his mate, Denton having retired months earlier. "We had a little giggle about it." A giggle, perhaps, but there was another reminder of the saying about time waiting for no man last week when Tommy Seymour left the international stage, and another one this week when Greig Laidlaw departed.
Watson has his head in Saturday's 1872 Cup game at Scotstoun but he's had pause for thought about the bigger picture all the same. "You never own the jersey, you borrow it and have it for a brief moment and it can all change in the blink of an eye," he says.
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"Sometimes when you're playing well you probably do take it for granted and sometimes it's only injury that wakes you up or when you see some mates retire. It makes you think, 'You'd better enjoy this while it lasts because it won't last forever'."
Laidlaw's exit brought a eulogy from Watson. "I'm absolutely gutted. It's been an honour to play alongside him. He's one of those players that when you're lining up with him you know that everything is going to be all right, he gives you that sense of security. He'll be sorely missed.
"I'd rather have nobody else captain me and that's not saying the other captains don't do the job. I've had some amazing captains, but Greig's leadership and passion for playing for Scotland was incredible."
'The shoe is on the other foot now'
There will be no shortage of passion at Scotstoun on Saturday, that's for certain. Edinburgh are on a roll on all fronts while Glasgow have had a lot of upset of late, most notably when they lost at home to La Rochelle last weekend and probably destroyed their own European Cup prospects in the process.
Edinburgh have won the last two 1872 Cups, but their most recent memory of playing Glasgow is pretty grim, a 34-10 hiding at the tail end of last season. "We've spoken about it," says Watson. "There are certain wrongs to be righted there.
"They're wobbling a bit and it's probably the first time in my eight years here that we go in as favourites. We know how fired up they'll be. We've been in that underdog position when people write you off. We've been in the situation where we weren't going well in Europe and we weren't going well in the league and this game becomes almost everything to us. The shoe is slightly on the other foot now.
"They're not going great in the league and not going great in Europe but they should have won both games against La Rochelle. If they end up losing both of these games, or even lose one of them, they're going to be in a very tricky position. The stakes are high for both of us."
Watson thinks he knows what's been going on in the Glasgow camp since the damaging loss to La Rochelle, the conversations they have been having and the person leading them. He returns to his old mate Wilson.
"I got fish-hooked by him one of the games last season," he says, with a smile. "He's the big leader there, he's going to be a key man for them. He'll be giving it out to us, stoking the fires as usual."
'Scotland have to be finished article'
The pair of them ought to be reunited in Gregor Townsend's training squad next month. Once the 1872 business is done and once the European qualification is decided, the attention will turn instantly to the Six Nations.
What great uncertainty lies within. Ireland, Wales, France and Italy have new coaches. And Scotland? The pressure after the failures of the 2019 Six Nations and the World Cup that followed will be enormous.
Watson saw less than 40 minutes of action in Japan before injury ended his tournament. "At the time you think it's the most gutting thing that's ever happened. I missed a World Cup I'd been looking forward to for four years, but the funny thing is that you get home and realise that rugby is not the be-all and end-all because I have a daughter, Honor, who had just turned one and she doesn't care about rugby. Nappies still have to be changed. The world goes on."
You sense that Scotland's inability to get some traction in the Six Nations is annoying him, though. "We feel like we're getting close sometimes, but it's no good getting close. At some point we have to become the finished article. There's no point in being a team that just attacks really well. Good teams get it done in whatever way necessary. We need to find that edge.
"Our defence has got to be better. If there's a time to do it then it's now because there's a lot of coaching changes going on in the other countries. We start in Dublin. If we're going to challenge for the title then we have to beat Ireland."
Beating Glasgow will do for now. He's waiting for a Wilson-led backlash, an angry performance that they'll have to be at their best to quell. Scotstoun was a bleak place last weekend when La Rochelle were in town. This one should be altogether different.