The Bianconeri said on their official website that examinations in Portugal revealed the five-time Ballon d'Or winner has suffered an "apparent minor injury to his right thigh flexors," but further tests are needed to determine how long he'll be sidelined.
The 34-year-old would be a big loss for manager Massimiliano Allegri, as he is the club's key attacking threat and top scorer this term.
Since signing from Real Madrid last summer for £99.2 million, Ronaldo has netted 19 goals in 26 Serie A games.
Mario Mandzukic is Juventus' next most prolific goalscorer in the league with eight.
The Croatian forward and Paulo Dybala will need to improve their form dramatically for them to cover for Ronaldo's absence.
Given Juve are 15 points clear at the top of Serie A, Ronaldo's injury is unlikely to prevent them winning an eighth consecutive Scudetto.
However, he will be a big loss in the UEFA Champions League should he be unavailable for either of their quarter-final legs against Ajax on April 10 and 16.
Ronaldo's hat-trick turned Juve's last-16 tie against Atletico Madrid in their favour after a 2-0 defeat in the first leg.
And, as the competitions's all-time leading goalscorer, the former Manchester United star is arguably the Champions League's most influential player ever.
Juve signed Ronaldo to help them win the famous trophy once again after they lost two of the last four finals, so they'll be desperate for him to be in top condition.