Vern Cotter bills himself as "just a Kiwi farmer" and he yesterday gave voice to the pragmatism that background implies by admitting that he would not have made any changes to the Scotland team that started against both Argentina and New Zealand over the past two weekends had matters not been taken out of his hands.

As things turned out, though, Cotter was forced to make four alterations to his starting line-up when he sat down to pick his side to face Tonga at Kilmarnock on Saturday in the match that will bring Scotland's viagogo Autumn Tests series to an end.

In total, four of the players who began both previous games have been declared unfit for active service against the Pacific islanders. But while it is not the scenario Cotter would have wanted, he seemed determined to make a virtue of necessity in his insistence that the players who represent Scotland in the World Cup year ahead will have to be able to display resilience and fortitude in the face of adversities that are all but inevitable.

"If there were no injuries I think it would have been difficult to change the group that performed well against Argentina," Cotter said. "And although we were disappointed with the result against the All Blacks, there were positive parts of our game. We were always aware that the New Zealand game might knock us around a bit.

"It has given some players an opportunity to show their talents, and that's exactly how it should be treated. They want to give their best for the team on Saturday against very difficult opposition.

"We're working with a group at the moment who I think are setting standards amongst themselves. That's good because when our players get pulled into the group these standards will have been set. The players have an understanding of what we want as well, which I think is important. We'll work together to try and keep the bar as high as possible."

The most experienced of the newcomers charged with that responsibility is the 90-times-capped Sean Lamont, who takes over at outside centre from hamstring injury victim Mark Bennett.

Tim Visser returns on the wing to take over from Sean Maitland, who has also picked up a hamstring problem, while in the pack Geoff Cross comes in at tighthead prop for Euan Murray (thigh) and Johnnie Beattie is given the No.8 shirt as Adam Ashe has a neck problem.

The continuity that Cotter likes is provided by the fact that three of those players - Cross, Beattie and Lamont - have been promoted from the bench. All played a part in the 24-16 loss to the All Blacks at Murrayfield last weekend, while Visser is getting his first taste of international action since bringing his cap count up to 14 - and his try count to seven - with two appearances on Scotland's visit to North America during the summer.

We will probably never know if complacency played a part in Scotland's humiliating 15-21 loss to Tonga at Pittodrie two years ago, the match that brought Andy Robinson's reign to a juddering end, but Cotter made it clear that he is alert to the possibility of a mental drop-off in Kilmarnock after two thunderous Tests in Edinburgh.

He was also adamant that the Tongans will be as helpful in providing a measure of where this Scotland team now stands as the All Blacks were six days ago.

"We need to get this game out of the way," said Cotter. "We said from the start that this would be the toughest game mentally: getting over the challenge of the All Blacks in front of 60-70,000 people, coming to Kilmarnock and playing on a synthetic surface.

"If anything we've looked at this a challenge to prepare for next year's World Cup, taking our rugby to England, playing Japan in the first game at Gloucester, moving outside of the certain comfort we have of playing at Murrayfield and being able to impose our game upon a team I think will offer us different challenges. Tonga are very strong physically and very disruptive at the breakdown, very confident after two good wins [against Georgia and the USA] not to mention the win they had two years ago.

"It's an important game for us and after that I think I could probably give you a fairer idea of where we're at."

While Scotland have unquestionably moved on from the nadir of losing in Aberdeen, Cotter recognises that the Tongans have taken strides too. Now ranked 12th in the world, the islanders would probably be placed even higher if they had a more favourable fixture list. Now helped by the presence of Jake White, who coached South Africa to a World Cup win in 2007, in their backroom team, they are moving closer to the mainstream of world rugby.

In 2012, Tonga still managed to pick up three yellow cards, but Cotter expects that Scotland's opponents will play a cleaner game this weekend. "The ref will referee what he sees in front of him," said the coach with a smile. "But Tonga will still target the breakdown. In the last two games they have and they've been effective and I think Jake White's had an influence on some of their higher tackles.

"They play a more structured game now. They play off lineout and scrum, they set phase attack, their defence comes up high and puts you under pressure. They're all professional now, their players are in France or New Zealand or wherever. They'll be a tough nut to crack.

"I think Jake would like to keep 15 players on the paddock."