Ronaldo stunners help Al Nassr in AFC Champions League thriller
Former Liverpool striker Sadio Mane and Anderson Talisca also scored for the Saudi side late Tuesday as they made it three wins from three in the group stages of the premier Asian club competition.
Talisca opened the scoring in Riyadh from the edge of the box in the 25th minute after being teed up by Ronaldo's clever back-heeled flick as the Portuguese talisman went through his full repertoire of tricks.
Mane turned and drilled home to add a second 11 minutes after the break and Al Nassr appeared to be cruising when Ronaldo curled home a sumptuous third from outside the box to make it 3-0 five minutes later.
But the Qatari side, inspired by former Barcelona and Liverpool winger Philippe Coutinho, scored twice in the next six minutes through Ismail Mohamad and Almoez Ali to leave the game on a knife-edge.
With nine minutes remaining, Ronaldo appeared to have had the final say as he sprinted onto a long ball from Sultan Al Ghannam and lashed home a superb left-foot volley without breaking stride.
There was still time for another twist as Michael Olunga pulled it back to 4-3 in the 85th minute to ensure a nervous final few minutes.
"When you face Ronaldo, there isn't much you can do," said Al Duhail manager Christophe Galtier, who was in charge of French giants Paris Saint-Germain last season.
'Best in the world'
"He scored two beautiful goals. I'm at a loss for words to describe him. What he did today is extraordinary for a 38-year-old. He's still the best player in the world."
Another Riyadh-based side, Al Hilal, made light of being without their injured superstar Neymar as they thrashed India's Mumbai City 6-0 with two goals from former Fulham frontman Aleksandar Mitrovic.
In the East zone, defending champions Urawa Red Diamonds of Japan were upset at home 2-0 by South Korea's Pohang Steelers, who netted either side of half-time in Saitama through Jeong Jae-hee and Goh Young-jun.
Urawa now face a battle to qualify for the knockout stages, having taken only four points from their three Group J games so far, level with China's Wuhan Three Towns, who beat Hanoi FC 2-1 for their first win.
"Today Pohang was the better team and deserved to win. Especially in the physical aspect, we couldn't do too much," said Urawa manager Maciej Skorza.
Japan's Kawasaki Frontale made it three wins from three with a 4-2 victory away to Thailand's BG Pathum United to open a three-point gap at the top of Group I over South Korea's Ulsan Hyundai.