Soldado was a team-mates of Punal during his season-long spell in Navarra five years ago and Punal believes he is outshining every other forward in Spain at the moment.
Punal told his club's website: "He is in a wonderful moment. He is scoring goals and everywhere he goes the ball seems to fall to him.
"Right now there is no better striker in Spain, but we also can't just concentrate on Soldado because Valencia have a great squad.
"We need to play a complete game because against Valencia a decent effort is not enough, they need to be 90 minutes at our top level."
Punal will return to the midfield after missing last weekend's 2-0 defeat to Racing Santander, as should Raul Garcia after he was only fit enough for an appearance from the bench. However defender Damia Abella is suspended.
Valencia boss Unai Emery is expected to field a full-strength side after all but sealing qualification to the semi-finals of the Copa del Rey in midweek with a 4-1 win over Levante.
Emery had rested some of his key players ahead of that match in last Saturday's 1-0 defeat to Real Sociedad, but has stressed he wants his players fully focused on the trip to Pamplona this weekend.
He told a press conference broadcast on the club's website: "The match will be very tough. Osasuna will force us to run a lot, and the moment in which we stop working so hard the chances of us losing go up. Right now all our energy should be concentrated on the next game."
Soldado missed the Sociedad game due to suspension so he and fellow goalscorer from midweek Jonas should return up front, but Pablo Piatti is a doubt with a knee injury.