With just three goals to their credit, Paraguay were the lowest scorers of any of the eight pool winners, although Martino's men only conceded once in their three Group F games.
Japan, who finished second in Group E, were not much more prolific, scoring one more goal and conceding one more than the South Americans, and the encounter in Pretoria could well be a tight affair.
- PARAGUAY v JAPAN: LIVE
Martino said: "I personally think that it's really important to score the first goal. "It is really decisive to score the first goal in the World Cup, especially when you get to the knockout stages, where with a win you stay and with a defeat you go home.
"If you have a goal scored against you it is very difficult to catch up knowing you only have 90 minutes to do so."
Neither side have reached the last eight of the World Cup before. Paraguay have reached the last 16 in three of the last four World Cups but so far have not been able to get any further.
When asked about the possibility of his side writing their names in national folklore, Argentinian Martino said: "Well of course we came to the World Cup with dreams and we're working on it, we're still in the race."
To achieve their goal, Martino believes it is vital they get one key area of their game right. "I believe if you want to aspire to something higher in the competition you must have better ball possession and use it better," he said.
"We're making a huge effort to improve our ball possession as I think this is the basis of our ambition in the World Cup. "We've succeeded in doing that in some matches and in others less so.
"If we have good ball possession and use it well, as well as putting pressure on our opponents, then we may win."
Japan coach Takeshi Okada believes his side have the ability to reach their first World Cup quarter-final. The Japanese have only once before reached the knockout stages of the World Cup when, on home soil in 2002, they were eliminated at the second-round stage by Turkey.
But the Blue Samurai are again in the last 16 in South Africa after beating Cameroon and Denmark to finish second in Group E behind Holland. That set up a showdown with Paraguay at Loftus Versfeld and for one of the nations a maiden appearance in the quarter-finals awaits. Okada is optimistic it will be his side making history, although he knows it will not be easy.
"It will be a challenge for us as we try to get into the last eight for the first time, so we will be doing our absolute utmost to address this challenge," said Okada, whose side were the first team to book their place in South Africa after a relatively comfortable qualifying campaign.
"Paraguay are solid in defence and quick in attack and it's clear they are good team because they finished first in their group but if we can deliver 100% of what we can do then I'm certain that we will be able to win.
"So I hope that physically and mentally we can give everything." Paraguay helped contribute to one of the biggest surprises of the tournament so far - the early exit of defending champions Italy.
The Italians finished bottom of Group F with Gerardo Martino's Paraguay going through as winners after beating Slovakia and drawing with the Azzurri and New Zealand.
Okada added of the South Americans: "In their group they were first amongst very good teams. All of them were very good and strong in their group and they finished first. "Many of their players play in European leagues and they're all good players and up front particularly they are very quick.
"Perhaps Paraguay aren't one of the most fancied teams but they are strong and good at going from defence to attack quickly, which is something we have to be careful about."