Ronaldo is not reported to be injured, so the shock move seemed to be tactical by Juve boss Andrea Pirlo, who has been under pressure in his first year as manager. Ronaldo started in Juventus' midweek 2-1 win over Atalanta in the Coppa Italia final.
Going into Sunday's final round of Serie A action, league champions Internazionale and second-place Atalanta had already qualified for Europe's biggest club competition next season.
Atalanta played AC Milan while Napoli took on 10th-place Hellas Verona.
The top four teams go to the Champions League while the fifth-placed side drops to the Europa League.
Portuguese star Ronaldo, 36, has one year remaining on his contract at Juventus but has been linked with a departure should they fail to qualify for the Champions League. He has scored 36 goals across all competitions for Juventus this season, and has 101 overall since joining from Real Madrid in 2018.