The Brazil star opened the scoring after a superb defence-splitting pass by Jude Bellingham on 40 minutes and then set up Federico Valverde for the all-important second goal in first-half stoppage time.
Gonzalo Garcia wrapped up the win late on with his second goal of the tournament, and the result means Xabi Alonso’s team end the first round of Fifa’s new tournament unbeaten.
They go through to the knockout stage as Group H winners on seven points, setting up a last-16 tie against Juventus in Miami on Tuesday.
Salzburg go out as Al Hilal of Saudi Arabia progress in second place behind Real, after defeating already-eliminated Pachuca of Mexico 2-0 in Nashville.
They next play Manchester City in the last 16.
Madrid are adjusting to life under new coach Alonso and were again without top scorer Kylian Mbappe, with the Frenchman thus far not having played at the Club World Cup as he recovers from illness.
But there was still plenty of star appeal for the 64,811 fans who filled Lincoln Financial Field in Philadelphia almost to capacity.
They reserved their loudest cheers for Bellingham and spirits were not dampened by wet conditions as the blistering heatwave of recent days suddenly lifted. (AFP)
