With a few days to spare, and the sort of computing power that NASA generally have at their disposal, you might just about work out the various permutations of results that could give Scotland a top-eight place in the world rankings by the end of this year's programme of autumn internationals.

Andy Robinson, however, has better things to do. The importance of being in the top eight is not lost on him, as Scotland's failure to achieve that precious status in 2008, when Frank Hadden was still in charge, meant that they were seeded as a third-tier nation at last year's World Cup and failed to reach the quarter-final stage for the first time. Yet he has reduced an issue of mind-addling complexity to a single imperative.

"We have to win at least two of the three games we are playing," was the head coach's firm assessment. Robinson was in Aberdeen on a mission to promote the third of those games, against Tonga at Pittodrie on November 24, and even he would probably concede that Scotland will be favourites to win. However, as the other two matches are against New Zealand and South Africa, getting a brace of victories looks like a fiendishly difficult task.

Argentina are the most obvious rivals for the eighth place Robinson wants, and they could lose ground in the rankings table in their remaining Rugby Championship games, against New Zealand and Australia, and in an autumn schedule that pits them against France, Ireland and Wales. Under another set of circumstances, Ireland could drop out of the eight, but Robinson was quick to point out that both sides could strengthen their positions over the next couple of months as well.

"I think that all 12 sides who have already qualified are tough sides to play," said the Scotland head coach. "We want to achieve the top eight, that's something we're striving for, but the only way we we are going to achieve it is by winning games. It could be taken out of our hands before then. We can only focus on ourselves and perform in the autumn, to look tactically at New Zealand and South Africa and figure out how we're going to beat them."

South Africa might look the softer target – Scotland beat the Springboks 21-17 in the autumn fixture two years ago – but Robinson took heart from Argentina's battling performance, albeit in defeat, in their Rugby Championship match against New Zealand recently.

"I love watching New Zealand play," he said. "They're right on the edge throughout the game, pressurising the opposition and the referee. International sport is about putting the opposition under as much pressure as possible because you get points from that.

"They're great at being able to accumulate points, but it was enjoyable seeing the way Argentina stood up to them for 50 minutes. [That] was really pleasing for us because it helps us think about our tactics when we play against them."

Robinson's only previous match in charge of Scotland against the All Blacks produced a 49-3 thrashing for the home side at Murrayfield – remarkably, it happened just a week before the win against South Africa. However, the coach was in buoyant mood as he reflected on the Scots' unbeaten summer tour to Australia, Fiji and Samoa.

"We're going to have to look at the tactics of how we play New Zealand and generate a belief among the players because of what they did over summer," he said. "I saw improvements in the way we defended against Australia, holding them out in the second half in the manner that we did. I liked the collective will of the players and their understanding of how to win a game.

"Against Fiji, it was the attacking threat that we had. We attacked really well in the first half and played with very quick ball. In the Samoa game we understood in the last 10 minutes how to win a game because the the effort of our defence and attack was to keep pressure on Samoa, who didn't leave their 22 in that last 10 minutes.

"It's now about putting that all together – defence, attack and putting the opposition under pressure – for 80 minutes. If you are involved in Scottish rugby, and in Scottish sport, you have to be able to enjoy the rollercoaster ride that you will be on during a game."

In that light Robinson experienced a downwards lurch yesterday when it was confirmed that Glasgow Warriors flanker Rob Harley, who scored the match-winning try on his debut against Samoa in June, had been ruled out of action for up to eight weeks after damaging knee ligaments in training. However, the coach pointed out that he is well covered in the blindside department now that Kelly Brown, who missed all of this year's RBS 6 Nations games through injury, is back playing again.

Robinson will refine his autumn Test squad selection after watching the opening rounds of this season's Heineken Cup. With the future of that competition thrown into doubt by the decision of England's top clubs to go it alone with a controversial broadcasting deal with BT Vision, the coach was guarded with his remarks, but stressed the importance of the Heineken tournament to Scotland's two participating sides.

"The English teams have to do what they have to do. But the European tournament has grown and has grown well," said Robinson. "It's a really exciting tournament to be involved in. For Scottish teams to have the success of Edinburgh last season, when we had 40,000 fans at Murrayfield, is what the Heineken Cup can do.

"Discussions are going on [in Dublin] next week and that's an important meeting for people to discuss what happens in the Heineken Cup post 2014. It's not for me to comment [on the English clubs' stance]. What is important is that we have two Scottish teams in the Cup."