Second-half goals from Adrian Lopez and Santi Cazorla were enough to hand a makeshift Spain side victory over Serbia in Saint Gallen.
Xabi Alonso had come closest to breaking the deadlock in a poor first-half with an audacious effort from well inside his own half that drifted just over the bar.
However, the introduction of Adrian on his international debut after the break provided the spark that the world champions needed as he first headed home Jesus Navas' teasing cross and was then brought down by Branislav Ivanovic to allow Cazorla to seal the victory from the penalty spot with 15 minutes remaining.
Vicente del Bosque surprised many with his selection from the start as he went for uncharacteristic 4-4-2 system with Alvaro Negredo and Roberto Soldado in attack. Juanfran also made his debut at right-back, whilst the other four uncapped players in the squad remained on the bench.
And it was Negredo who made a much more positive impact of the front two in the first 45 minutes as he forced Dahir Kahriman into his only serious stop of the first period with a fierce shot form 20 yards after just two minutes.
The Sevilla striker came close again 12 minutes later as his header from Alonso's fine cross lopped over the bar, but the assistant referee's flag had been raised in any case.
Alonso himself then saw a spectacular effort dip just too late as from midway inside his own half he spotted Kahriman well off his line and came with inches of scoring an unbelievable goal.
Unfortunately, that was about as exciting as the first-half got as Negredo saw another effort trickle wide, whilst Serbia's only attack saw Dejan Lekic put the ball in the net but he had already been rightly flagged for offside.
Negredo, Soldado, Alonso and Sergio Ramos were all replaced at the break as Del Bosque handed first caps to Alvaro Dominguez and Benat and also introduced Adrian and David Silva.
The latter two combined to present Adrian with a great chance just after the hour mark as Silva perfectly picked out the Atletico Madrid striker's run but he blasted over with just Kahriman to beat.
Two minutes later though Adrian had made amends as Benat's fantastic pass over the top freed Navas down the right and his cross was perfectly measured for the former Deportivo La Coruna man to easily head in.
Javi Garcia then replaced Bruno to take the number of Spanish debutants to five and a satisfactory evening for Del Bosque was assured when Ivanovic was harshly penalised to clipping Adrian's heels inside the area.
The Chelsea defender did not appear to make much contact with the Spanish striker but his complaints were futile as Cazorla fired the penalty straight down the middle to register his fifth international goal.
Del Bosque will name his final 23-man squad tomorrow ahead of two more friendlies this week against South Korea and China before the Spanish begin the defence of their European crown against Italy on June 10.