Not since the Portuguese superstar played for his first club, Sporting, in 2002 has he featured in the Europa League - then the UEFA Cup - but that now appears to be a very real possibility.
Juventus' 3-0 home defeat to AC Milan on Sunday left Andrea Pirlo's side in fifth place in Serie A, one spot outside the Champions League places, and now relying on teams above it to drop points in the final three games of the season.
Only three points separate Juventus in fifth and Atalanta in second, but the Old Lady's tricky run-in features newly-crowned champion Inter Milan and a dangerous, in-form Sassuolo side.
Ronaldo and Co. need to win all three of their remaining games and hope that one of Napoli, AC Milan or Atalanta drop points along the way.
Pirlo has been widely criticized for Juventus' form this season, which included a shock elimination to Porto in the Champions League round of 16 and a failure to win Serie A for the first time in 10 seasons.
This is the 41-year-old's first job in management following a storied career as a player, but many questioned the decision to promote him from Juventus' U23 side after just nine days following the dismissal of Maurizio Sarri as head coach of the first team.
"I saw the team in good spirits this week, we had trained with the right concentration and we were convinced we could play a great match," he told reporters after the game. "However, it was not like that, after a few episodes we became disunited and many things did not work.
"I knew we were going to run into difficulties, but now we all have to get out of this together. There must always be pride in wearing this shirt and certain performances must not be there. I had a different project in mind, I tried to work according to certain principles, at times we had to adapt, but I am convinced that I have an excellent team at my disposal.
"If something went wrong, I take responsibility for it."
The season isn't over entirely, however, with the Coppa Italia final still to play against Atalanta on May 19.
Ronaldo's current contract runs until the end of next season, but there have been reports the 36-year-old is keen to return to Sporting. However, Juventus managing director Fabio Paratici insisted earlier this year that the club would be "holding on to him," despite its struggles on the pitch.