After returning from knee surgery shortly before the tournament, Torres was overshadowed by strike partner David Villa in the European champions' three Group H matches and looks well short of his devastating best.
While Villa netted three times, including two of the finest goals so far in South Africa, Torres squandered several chances and looked a shadow of the player who scored a brilliant winning goal in the Euro 2008 final against Germany.
"It's not easy coming back after an operation," the 26-year-old said in an interview with Spanish radio on Saturday.
"I think I still have a little way to go before I am back at 100 percent, although I am close," he added.
Vicente del Bosque is likely to keep faith with Torres alongside Villa in a two-pronged attack as the Spanish seek to become the first team to score against the resilient Portuguese at this World Cup.
The Spain coach has been at pains to point out that there is more to Torres than goals, noting that the powerful forward has an important role in sowing chaos among defenders.
"The main thing is that he played in the three (group) matches, he has been making progress in his preparation and he is better," Del Bosque told reporters on Saturday.
"He may not have scored but he helps us by being a menace for the opposition's defence," he added. "And when he gets into space he is always a very dangerous player."
INJURY CONCERNS
Spain and Portugal, who have never met at a finals, know the winners at Cape Town's Green Point Stadium will avoid the big guns with Paraguay or Japan waiting in the last eight.
Del Bosque and Portugal coach Carlos Queiroz both have injury concerns, with Spain midfielder Xabi Alonso doubtful after spraining an ankle against Chile and Portugal winger Danny struggling with a left thigh injury.
Midfielder Deco has recovered from the hip problem that ruled him out of Portugal's final two Group G games and Spain central defender Raul Albiol, who has been an unused substitute thus far, is sidelined after being injured in training.
Portugal also have seven players on yellow cards: Cristiano Ronaldo, Pedro Mendes, Hugo Almeida, Pepe, Tiago, Fabio Coentrao and Duda, while the Spanish have not collected a single caution.
Midfielder Javi Martinez, who would likely replace Alonso in Spain's starting lineup, also jumped to Torres's defence.
"Fernando has been bringing a lot to the team," the 21-year-old, who was a surprise inclusion in the squad and has made only three appearances for the European champions, told a news conference on Sunday.
"The space he opens up is fantastic for us and I am sure he will rediscover his top form in the next few matches."
The showdown in Cape Town has an intriguing subtext as Queiroz was the man Real Madrid president Florentino Perez brought in to replace Del Bosque when he ditched him at the end of the 2003 season.
Del Bosque had steered Real to two European Cups and two league titles in 3-1/2 years and was upset at his treatment, which he called "unjust, aggressive and insensitive".
Real captain Fernando Hierro, who was also discarded in the cull, is now the Spanish national team's sporting director.
David Villa flying high for Spain
Spain defender Albiol injured in training
Torres unlikely to play in Spain opener
Drogba to decide whether to play against Portugal
Injured Alonso doubtful for Portugal clash