"True champions never break!" Ronaldo said on Instagram with a photo of him training ahead of Sunday's Serie A game away to Cagliari.
The title of greatest goalscorer is much contested, and global governing body FIFA does not keep an official record, but several media outlets reported that Ronaldo's strike had taken him past Austro-Czech Josef Bican to the top of the list.
World champions France went top of Group A3 with 13 points from five games, three ahead of Portugal and with the better head-to-head record to give them an unassailable lead. It was only Portugal's second defeat since the 2018 World Cup.