The two SPL sides, both funded by the Saudi Public Investment Fund, underwent huge summer spending sprees ahead of this much-anticipated clash.
Ronaldo, the December signing from Manchester United, was joined at Al Nassr by former Liverpool man Sadio Mane, while Manchester City treble winner Aymeric Laporte quickly became the league's best defender.
So when they lined up against Firmino, Riyad Mahrez, Allan Saint-Maximin and Spain starlet Gabri Veiga of Al Ahli, the excitement in Riyadh was huge.
So much so, in fact, that the first goal couldn't even be seen.
Flares engulfed the Al-Awwal Park for the opening stages of the match, and when Mane played Ronaldo through on goal inside four minutes, former Chelsea goalkeeper Edouard Mendy wasn't even visible to the naked eye.
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Whether Mendy could see or not is another question, but Ronaldo didn't care, running off for his 'SIUUU' celebration with the stadium joining in.
The goal was football's all-time top scorer's eighth in seven games, while he even has four assists to boot in that time.
Talisca later made the game 2-0 before half time, putting Al Nassr on course for a fifth league win on the bounce, helping them close down Pro League leaders Al Ittihad.