April might be the cruellest month, but Movember - formerly known as November - is the silliest as far as rugby players are concerned.

Being chosen for his first Test at Murrayfield should have been a serious occasion for Tim Swinson, but the gravitas of the Glasgow Warriors lock was fatally undermined when he arrived in the hospitality suite at Murrayfield yesterday sporting a set of muttonchop whiskers that suggested he had just strolled over from the set of Downton Abbey, Gangs of New York or Young Winston.

Fortunately, the Swinson video collection also includes footage from Scotland's bout with South Africa in the Mbombela Stadium in Nelspruit last June. If ever a game confirmed a player's fitness for purpose at the highest level then this was it, for Swinson put in a magnificent shift on his international debut, a performance of measured ferocity throughout. Some of us had wondered if the 26-year-old rookie could match the Springboks' fire; for much of the game Swinson actually quenched it.

In light of which, interim head coach Scott Johnson slept easily in his bed on Monday night after choosing Swinson to partner Al Kellock ahead of Richie Gray, Scotland's only current Test Lion, for Saturday's match against Japan. Gray's status as the outstanding Scottish forward of the age is undiminished, but Johnson can be sanguine about leaving him on the bench for the opening match of Scotland's autumn series.

Of course, with the Springboks due in Edinburgh next week, Johnson may well revert to his favoured Six Nations pairing of Gray and Jim Hamilton, tempted by the extra ballast those two will bring to the Scottish second-row. The athleticism of the Japanese forwards is their greatest threat, so Swinson and Kellock represent the horses-for-courses option this weekend.

Yet Johnson also hinted that he had favoured home-based players - Gray and Hamilon play for Castes and Montpellier respectively - as that made the team's preparations easier. "One of the big decisions was how much training we could get in with the team available," said Johnson. "That was a major contribution to the team we've picked. We got an extra session out of them. It's a funny way to pick things, but we wanted to make sure that people got runs on the board.

"I said from the start that there will be some constants in this programme, and the rest will be done on form and an eye to the future. It's a balancing act, but it was that extra training run that swayed things in a few cases."

Swinson was one of 10 players who earned first caps on Scotland's summer visit to South Africa. Of that group, only he and Tommy Seymour, the Glasgow wing, will be in the starting lineup on Saturday. Two others - Glasgow hooker Pat MacArthur and Saracens utility back Duncan Taylor - will be on the bench.

Johnson described the tour, in which Scotland also played Castle Incoming Series matches against Samoa and Italy, as a "wonderful" experience. However, Swinson suggested that a Murrayfield cap would be like another debut, another box ticked by a player who admits that a level of self doubt still bubbles beneath his confident exterior.

Did 80 minutes of action against the Springboks convince him he was a Test animal? "It was actually the first tackle," he smiled. "One thing I still wonder about when I play is whether I deserve to be there. I know it is stupid after my career already that I think that, but after the first tackle in South Africa I thought, 'Yeah, this is not that too bad. I can do this.' After that I was fine."

Seymour echoed Swinson's point that a first home appearance belonged in a different category to one on a foreign field almost 8000 miles away. "Obviously, I got a strong buzz running out against South Africa," the winger commented. "But this is going to be another thing altogether.

"Ever since I started to get into Scotland squads it has been the dream to run out at Murrayfield in front of the home crowd. It is something very, very special and it will live with me for a long time."

Astonishingly, Seymour has never played at the national stadium. Now in his third season with Glasgow, he has missed the two 1872 Cup matches his team has played against Edinburgh there. He was 24th man for Scotland against New Zealand a year ago, so knows the international build-up routine, but the Japan game will be his first taste of international action at Murrayfield.

"I've watched a few games here," he said. "When I was 24th man I warmed up on the pitch and then took my place in the stand. As much as a player who has never played here can, I am aware of what the atmosphere will be like and what it is like to play here. It will be a great occasion."

Seymour also appreciates that his place in the team owes something to the injury suffered by Tim Visser two weeks ago. Sean Maitland has also dropped out of the reckoning as a rival on the wing as, with Stuart Hogg and Peter Murchie out of action, he has to play at full-back. Yet Swinson knows he would press a strong case for being retained for the long-term if he marked his first Murrayfield appearance with his first Murrayfield try.

Seymour said: "I would be lying if I said it would not mean a lot for me to get a try at international level for Scotland, especially at Murrayfield. It would be serious icing on the cake for me.

"In order to do that we have to go out and play well as a team, with the forwards getting the ball for us and the backs playing well. If that all happens then hopefully someone like me can go out and get a try, which would make me very happy."