The Portuguese star, without a goal in his past three appearances for the Saudi Arabian side, netted the second of the hosts' goals at Al Awwal Park in Riyadh.

Right on the half hour, Al Ain goalkeeper Khalid Essa failed to hold a routine long-range drive from former Liverpool forward Sadio Mane, leaving Ronaldo to pounce on the rebound to tap home.

The win maintained Al Nassr's unbeaten start to the rebranded AFC Champions League Elite, lifting them to third in the 12-team West Asia table. Saudi counterparts Al Hilal and Al Ahli sit above them. The top eight reach the knockout phase.

Seeking revenge following last season's quarter-final exit at the hands of Al Ain, Al Nassr burst out of the blocks on Tuesday. Stefano Pioli's side took the lead after five minutes, when Brazilian Anderson Talisca finished low past Essa from the edge of the Al Ain area.

After Ronaldo doubled Al Nassr's advantage, the home team put the result beyond their UAE rivals seven minutes later. Angelo Gabriel, a summer signing from Chelsea, exchanged passes with Mane and sent his shot looping over Essa courtesy of a deflection off Al Ain defender Fabio Cardoso. It was eventually deemed an own goal.

Al Ain pulled one back at the start of the second half, when Park Yong-woo's shot struck the upright and cannoned back off Al Nassr goalkeeper Bento for the game's second own goal.

However, Brazilian teenager Wesley, introduced moments before, curled home eight minutes from time before Talisca rounded off the night deep into stoppage time with his second.

With the loss, Al Ain languish at the bottom of the West Asia standings having taken a solitary point from a possible 12. A third successive defeat ramps up the pressure on manager Hernan Crespo, who in May guided the club to a first Asian crown in 21 years.