Both Spain and France head into the the clash at Atletico Madrid's Vicente Calderon stadium with 100% records from their opening two matches.
They are both already two points clear of third-placed Georgia, who have also played a game more, and with Finland and Belarus the other sides in Group I, it is hard to see anyone else challenging the big two for top spot.
Therefore, the two matches between Spain and France inevitably take on added significance, with any slip likely to prove costly.
Del Bosque said of Tuesday's match: "We want to take a step closer to qualification. It seems that one of the two countries will qualify in top spot and so it becomes a knock-out cup tie.
"When we finish tomorrow's [Tuesday's] match there will still be a lot to play for, but it seems these two matches against the French are vital."
The two nations had mixed fortunes on Friday night with Spain claiming a 4-0 qualifying win away to Belarus on the back of a Pedro Rodriguez hat-trick while France slipped to a surprise 1-0 friendly loss at home to Japan.
It remains to be seen whether Del Bosque opts to retain a winning line-up, with Andres Iniesta, Fernando Torres and David Villa among those who started on the bench on Friday, but he may be forced to make at least one change due to injury.
Sergio Ramos, who was replaced by Raul Albiol in the second half against Belarus, missed training yesterday and remains a question mark for Tuesday.
Del Bosque said of Ramos at the pre-match press conference: "He's going to train later, but if he can't play we won't force the issue, we won't take any risks."
With the first-choice duo of Carles Puyol and Gerard Pique already injured, the loss of Ramos would further stretch Spain's defensive resources and it could mean another new-look pairing at the back, with Albiol, Javi Martinez and Sergio Busquets the main options.
If either Ramos or Albiol play they are likely to line-up against a familiar figure in the form of Real Madrid team-mate Karim Benzema - a player Del Bosque admires greatly.
"He's one of the great strikers in the world. He plays easy, he has very good technique. Like every player he has lapses, but he's one of the best," said the Spain coach.
Spain have won their last three matches against the French, with the most recent meeting being a 2-0 victory in the quarter-finals of Euro 2012.
Since that match France have seen Didier Deschamps replace Laurent Blanc as coach, but the new man in charge is under no illusions just how difficult it will be to end their losing run against the reigning world and European champions.
He told AS: "There is a big difference in the level between the two. We only need to look at the results to understand that.
"When Spain won the World Cup, our team were knocked out in the first phase. What Spain have done in the last four years nobody has ever done.
"When we met in the European Championship, Spain deserved their victory. Five months later, I don't know if we've improved enough to be able to beat them, but we will try.
"After the disaster of the 2010 World Cup, we are building a team to arrive well at Brazil. That's the objective."