Spain need to win their Group H clash against Chile to be certain of going through to the second round.
The 2008 European champions were expected to make it through their group with ease to justify their tag as likely winners of the World Cup this time around.
But it has been a tougher route than first thought for the Spanish, with a second-place finish meaning they would probably face a mouth-watering clash against Brazil in the next phase.
Their shock 1-0 defeat to Switzerland was one of those days for the team, failing to create enough significant chances despite dominating possession, with the Swiss taking their opportunity with aplomb to cause a real stir.
However, they appear to have rectified the situation with a 2-0 victory over Honduras, although it should have been by a lot more, with Fernando Torres missing several chances to open his account and two-goal hero David Villa putting a penalty wide.
Torres' lack of sharpness has been a particular worry, with the prolific Liverpool striker still seeming to struggle for his best form having had to undergo knee surgery in April.
This has been coupled with complaints from former coach Luis Aragones over Vicente Del Bosque's decision to field two holding midfielders in Xabi Alonso and Sergio Busquets behind playmaker-in-chief Xavi, stating his tactics to be too negative for a side with so much attacking ability.
Spain will know Chile have the ability to cause another upset having played some of the best football of the tournament so far, and also need a point to be certain of qualifying through the group.
They may have only won their two matches 1-0, but players such as Alexis Sanchez, Matias Fernandez and Jean Beausejour have all impressed enough to suggest that they could pose a significant threat to Spain's backline.
Their bright, enterprising style under Marcelo Bielsa was a joy to watch in their opening match against Honduras, although their lack of a clinical finisher could hamper their prospects of going far in the competition.
Del Bosque is expected to bring Andres Iniesta back into the starting line-up after the Barcelona playmaker recovered from a knock sustained against the Swiss.
Whether the Spanish coach will change his tactics to accommodate both Iniesta and Jesus Navas, who has impressed on the right side of midfield, is yet to be seen, but he may be tempted to leave out the more defensive minded Busquets to give Iniesta a role in the centre of midfield.
Torres is likely to partner David Villa up front after FIFA decided not to take action on the Barcelona new boy following his slap on Honduras defender Emilio Izaguirre.
The versatile Alvaro Arbeloa may also be brought in at left-back to replace Joan Capdevila, with the Real Madrid defender's physical nature more beneficial to tackling the tricky Sanchez.
Chile will be without midfielders Carlos Carmona and Fernandez through suspension, with Jorge Valdivia likely to fill in one of the roles.
Despite suffering from a lack of form and fitness during the tournament, striker Humberto Suazo is set to remain in attack for Bielsa's team