Borussia Dortmund concluded their mid-season break in Marbella with a routine 3-0 win over Standard Liege on Thursday.
Thomas Tuchel's men registered a convincing 4-1 victory against PSV in Cadiz on Saturday and they picked up where they left off at the Estadio Municipal.
Teenage USA international Christian Pulisic opened the scoring after 15 minutes, latching on to a superb pass from Lukasz Piszczek and dinking a finish over Standard goalkeeper Guillaume Hubert.
Sokratis Papastathopoulos had earlier headed against the crossbar but the Dortmund centre-back was forced off with an ankle knock before the half hour.
Tuchel made wholesale changes at the interval, when Standard's reported Everton target Ishak Belfodil was also withdrawn.
Dortmund rarely looked like losing their grip on the contest and another 18-year-old, Felix Passlack, beat three defenders on an excellent solo run before drilling home to make it 2-0.
Raphael Guerreiro, who spent the past two months on the sidelines with muscular problems, completed the scoring 17 minutes from time when Hubert pushed Mikel Merino's drive back into the area.
Dortmund lie sixth in the Bundesliga and resume their league campaign at Werder Bremen on January 21, after next week's friendly at Paderborn.