The world and European champions have won all five of their Euro 2012 qualifiers to date but have noticeably taken their foot off the gas in friendlies since winning the World Cup last July.
A month after their triumph in Johannesburg it took a last-minute David Silva goal to rescue them from a defeat away to Mexico, while it got much worse in the autumn when they conceded eight goals in friendly defeats to Argentina and Portugal.
That defeat to the Argentinians was just their third since 2006. Switzerland inflicted the previous one in the first game of the 2010 World Cup, and before that the last side to beat them were the Americans at the 2009 Confederations Cup.
Midfielder Xabi Alonso has warned his team-mates they must ``learn the lessons'' of that defeat and Del Bosque insists his team have a reputation to uphold.
He told Diario AS: "We have had bad experiences (in friendlies) but it should teach us that the demands on us are great.
"The stain of the defeat to Portugal must not be repeated. We learned that we cannot put at risk the prestige gained in the World Cup with painful defeats in friendlies. We should be very careful about that.
"In these games there are no points at stake but there is prestige, and to defend that is equally important.
"Spain now plays with a greater responsibility than it did before, and that is because we have won the World Cup and the European Championship.''
Former Real Madrid boss Del Bosque has warned his team not to underestimate the USA, who reached the last 16 at last summer's World Cup and are using this friendly as preparation for their participation in the CONCACAF Gold Cup on home soil.
The tournament begins this weekend, with the US kicking off their campaign against Canada on Tuesday.
"We must pay close attention and put in plenty of effort, it will not be an easy match,'' Del Bosque said.
"The US have a good coach (Bob Bradley) and good players, they are sure to have extra motivation to play against the champions and to do so in Boston, in their country.
"They play strong football and they are uncomfortable to play against, they are fast, tall and have a good physical condition.''
Spain will be without Barcelona duo Carles Puyol and Xavi, with the former requiring knee surgery and the latter rested after a heavy programme for club and country over the last few years.
Midfielder Manu Del Moral, who last month joined Sevilla from Getafe, has been called into the senior squad for the first time while there are recalls for Villarreal pair Bruno Soriano and Borja Valero and Sevilla forward Alvaro Negredo is also back in the mix.
Del Bosque, whose side also take on Venezuela on Tuesday, insists his squad are in good shape despite these games representing the last action of another long, hard season for many of them.
"They are tired, but all our international are physical marvels, as well as very big players,'' he said.
"The season ended a week ago and nobody could get out of shape. The team is well, they have physical and technical tone.''
Del Bosque's American counterpart Bradley is unlikely to be too experimental in his selection with the Gold Cup campaign starting in less than a week.
Bradley told sportingnews.com: "When you consider that guys have come in late, probably you need to really concentrate on the things we've done that are established, that are solid, and build on that as opposed to thinking that there's time now to be throwing altogether new things into it.''