Gareth Bale scored in the 44th, 53rd and 55th minutes at the Zayed Sports City Stadium.
In his last nine matches, Gareth Bale has been taken off seven times, five of those when Real Madrid were chasing a goal.
Real Madrid set the record for the longest goal-drought in the club's history during a surprise 2-1 defeat by Levante.
After eight games in La Liga, Barcelona are second with 15 points while Real Madrid are fourth with 14 points.
Gareth Bale will not be available for Wales vs Republic of Ireland Nations League clash.
Paco Alcacer netted twice in the first half to make it eight goals in 14 Spain appearances.
Bale has been troubled by a groin injury in recent weeks and was forced off in the closing stages of Real Madrid's defeat at Alaves.
Gareth Bale and Kevin De Bruyne were among the first 10 nominees for the Ballon d'Or award announced on Monday.
Madrid have gone three games without scoring, after their surprise Champions League loss to CSKA Moscow on Tuesday followed a draw against Atletico Madrid and defeat to Sevilla.
Gareth Bale picked up a thigh injury during the goalless draw with Atletico Madrid on Saturday and had to come off at half-time.
Real Madrid confidently launched their pursuit of a fourth successive Champions League title with a 3-0 win over AS Roma.
If the summer had gone differently, Gareth Bale might have been on a plane to Switzerland on Monday to play for Manchester United against Young Boys.
Gareth Bale has shone in the spotlight since Cristiano Ronaldo's departure for Juventus, scoring in all of Real's opening three La Liga wins.
France were held to a 0-0 draw by Germany in Munich in a flat start to the new UEFA Nations League.
Real Madrid have taken maximum points from their opening 3 fixtures in contrast to the same point last season when they were already 5 behind Barcelona.
Karim Benzema netted twice and Gareth Bale scored a trademark goal as Real Madrid overcame an early scare at Girona to win 4-1.
Marco Asensio entered the game at the start of the second half and scored less than two minutes in before adding another in the 56th minute.
Real Madrid coach Zinedine Zidane said his side's third successive Champions League title was "something crazy" after the Spanish giants defeated Liverpool 3-1 in Saturday's final in Kiev.