Isco wasted little time in justifying Zidane’s faith, the Spain star escaping down the left before cutting the ball back for Ronaldo to prod home a clever finish.
Juve responded well to the setback, with Sergio Ramos making a fine tackle to deny Dybala a clear chance before Rodrigo Bentancur scuffed a shot after being teed up by Gonzalo Higuain.
Higuain thought he had levelled against his old club 22 minutes in, but a brilliant reaction save from Keylor Navas denied the striker from close range, before Toni Kroos blasted a shot off the crossbar on a rare Madrid break.
Juve felt they could have had two penalties just before half-time, but referee Cuneyt Cakir decided Casemiro did not deliberately handle a Giorgio Chiellini header and then booked Dybala for diving when he went to ground easily in the box.
The home side continued to press early in the second half, Dybala watching a free-kick deflect agonisingly wide after a foul by Ramos, who picked up a booking that will keep him out of the second leg in Spain.
The match was taken out of Juve’s hands in the space of two minutes. Ronaldo acrobatically fired Dani Carvajal’s cross into the net from 12 yards out, earning applause from all corners of the Allianz Stadium, and Dybala’s high foot on Carvajal saw him dismissed soon afterwards.
With the home crowd stunned, Marcelo combined first with Isco and then Ronaldo before clipping the ball over Buffon and blasting home on the line with 18 minutes remaining.
Mateo Kovacic hit the bar from the edge of the box and Ronaldo missed a golden chance to get his third, volleying over unmarked from barely six yards out, but the damage had been well and truly done