The Blaugrana boss is refusing to be drawn in on the shot stopper's mistake against Real Madrid, and also spoke about Alexis Sanchez's early-season form.
The Catalan giant goes into the encounter following the 3-2 first-leg win of its Supercopa Espana tie against Real Madrid, but its task of lifting the first domestic silverware of the season has been made more difficult due to the custodian's error, which gifted the capital side a late second goal.
However, speaking in a press conference, Vilanova insisted Valdes' error has been blown out of proportion and reminded critics of the goalkeeper's role in helping the side to three successive Liga crowns between 2009 and 2011.
"It surprises me that Victor is being doubted, even though we have won three Liga titles thanks to him," said the Barca boss. "I have seen him play very well so far this season; he is very strong mentally."
Vilanova also leaped to the defense of winger Alexis Sanchez, who struggled to exert much influence on proceedings at Camp Nou last Thursday.
"I agree that he did not play well the other day, but he did the things that we asked of him and really helped us," he added. "Perhaps he lacked a ruthless edge, but I'm sure he will do very well this season."
Regarding Sunday's trip to Pamplona, Vilanova acknowledged the pitfalls that face his side, as he cast his mind back to last season's 3-2 defeat at the Reyno de Navarra, when he was assistant to former coach Pep Guardiola
"It is a complicated match because they are a closely-knit team," he said. "My players have been warned of the dangers Osasuna pose and they know that last year we threw away the league at this venue."
Vilanova could hand a debut to Alex Song in Sunday's encounter, but he warned the former Arsenal man may need some extra time to build his sharpness before turning out for his side, which started its league campaign with victory over Real Sociedad last weekend.
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