It was a frustrating match for Ronaldo, who had many chances to put Al-Nassr further ahead, but he missed several chances, including one that hit the post.
Al-Tai soon fought back to score the equaliser late on and it looked like the teams were set to share the spoils, but Ronaldo and Al-Nassr were given one last chance to seal the win when the referee awarded a penalty for a handball.
The Portugal hero stepped up to fire into the back of the net, securing a 2-1 win and taking his goal tally up to 10 in the Saudi Pro League this season.