"This chapter is over," Ronaldo cryptically said on social media with a photo of him in an Al-Nassr shirt.
Ronaldo, the top scorer in this season's Saudi Pro League, has eight in seven appearances in this campaign's Champions League Elite, one short of joint-top scorers Riyad Mahrez, Salem Al-Dawsari, Anderson and Jasir Asani.
The 19-year-old forward, who trains daily alongside one of football’s all-time greats, is part of a promising Saudi Arabian generation aiming to make a statement on the global stage.
Al-Nassr remain in the third place with 54 points but they are now three points behind second-placed Al-Hilal and seven off leaders Al-Ittihad, who visit Al-Ahli on Saturday.
Cristiano Ronaldo's Saudi side Al Nassr were on Monday drawn against last season's runners-up Yokohama F-Marinos of Japan in the quarter-finals of the Asian Champions League.
Ronaldo, the Al Nassr captain, was reportedly rested for last week's goalless draw in the first leg in Iran, however returned to lead the side at Al Awwal Park.
Ronaldo turned 40 last week with his current contract due to end in June 2025.
Al Nassr captain Ronaldo had looked destined to endure a hugely frustrating game following a series of missed opportunities in the first half at Al Bayt Stadium.
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.
Al Hilal, who lost Neymar Junior to injury in October, beat bottom-placed Al Hazm 4-1 to go an unbeatable 12 points clear of Ronaldo's Al Nassr with three matches remaining.
Ronaldo was once again the star performer for his side and was as clinical as ever in front of the goal. The 39-year-old was too hot to handle for the Al-Wehda players who completed the 66th hat-trick of his illustrious career.
Superstar Cristiano Ronaldo ended a two-game goal drought as he scored a brace to help his Saudi Pro League side Al Nassr to a 3-1 win Al Khaleej in the semifinal of the King’s Cup of Champions on Wednesday.
Portugal's record scorer was shown a straight red card four minutes from time for elbowing an opponent when his side were 2-0 down before they scored a late consolation.
The 39-year-old scored back-to-back hattricks in three days.
Al Nassr striker Cristiano Ronaldo has once again silenced his critics after grabbing a hat-trick. The 39-year-old scored three second half goals against Al Tai to bring up 33 goals in all competitions this season for the Saudi outfit.
Cristiano Ronaldo, who had just recently become the first footballer to achieve 800 career wins, was included in the Portugal squad for the upcoming friendly matches against Sweden and Slovenia.
The 39-year-old Portuguese was the only Al Nassr player to score in the shootout as his Saudi side went out 3-1 on penalties, the tie having ended 4-4 on aggregate.
Nassr, who won last week's first leg 1-0 thanks to a Ronaldo goal nine minutes from time, were the better side at Al Awwal Park and took the lead on 17 minutes through Portuguese winger Otavio.
Cristiano Ronaldo scored his 21st goal of the season and his fourth in the Asian Champions League on Wednesday as his moment of magic proved decisive in Al Nassr beating Al Fayha 1-0 in an all-Saudi last 16 tie.
