Yet a closer look shows that their Group C opponents Australia, Denmark and France should treat Peru with healthy respect, even though they will all expect three points after news of Guerrero's absence for doping.
"We will without doubt miss Paolo in Russia but we are convinced that our team, with its courage and tenacity, will do Peru proud," the Peruvian Football Federation said.
Guerrero had just completed a six-month ban after testing positive for cocaine contained in a tea he drank when the Court of Arbitration for Sport (CAS) extended the suspension, ruling him out of the World Cup.
The world players' union FIFPro and the captains of Peru's group rivals have appealed to FIFA to lift the ban.
Clear underdogs at 200-1 to win the World Cup, Peru are ranked 11th by FIFA and have been growing in confidence after a storming end to the two-year South American qualifiers.
A 2-2 draw away to Venezuela in March 2017 set Peru on an unbeaten run that saw them pip Chile on goal difference for fifth spot then beat New Zealand 2-0 in a two-legged playoff.
Since then, Peru have claimed two European scalps -- Croatia and Iceland -- in friendlies to prove their place at the finals was no fluke.
"We will face teams loaded with top-level players," said coach Ricardo Gareca, who broke Peruvian hearts when his goal for Argentina stopped their team qualifying in 1986 but has now become a national idol. "But we have top-level players, too."
Even without Guerrero, Peru still boast talents such as Jefferson Farfan, a 33-year-old winger with Lokomotiv Moscow, and Renato Tapia, a self-confident 22-year-old with Feyenoord who can play in midfield or defence.
Despite Peru's technical ability, work ethic and quick passing, beating or even holding France to a draw may be a step too far.
They should not be daunted, however, by Denmark, who also reached the World Cup via a playoff and are Peru's first opponents at Saransk on June 16. Neither will they fear Australia in their final group game in Sochi.
"Nothing has been nor will be easy," said Tapia, assessing Group C.
Gareca, 60, a familiar sight with his long hair and animated gestures, wants his close-knit team to assuage Peru's historical anguish at being away from the finals for nearly four decades.
"I want us to boss matches, whoever and wherever we're playing," he said.
(Reporting by Andrew Cawthorne and Diego Ore; Writing by Andrew Cawthorne; Editing by Ken Ferris)
