Cristiano Ronaldo trains with son Cristiano Junior ahead of Juventus' Serie A season opener

It was like seeing double as the pair took part in running drills

Juventus forward Cristiano Ronaldo has been recovering from injury. AFP

Cristiano Ronaldo has had a frustrating spell out injured during pre-season, but the Juventus star has at least been able to call upon a "special training partner" as he works his way back to full fitness.

The Portuguese sat out out his side's friendly victory over Serie C team Triestina in Italy on Saturday as he recovers from a muscle problem.

Instead he was at Juventus's training ground where he was joined by son Cristiano Junior, who took part in running drills.

Alongside the video posted on Instagram, Ronaldo wrote: "Working hard on my recovery with a special training partner!!"

The youngster has already shown plenty of signs of following in his father's footsteps as a footballer, with Ronaldo senior posting other videos of his son's skills.

Last year he tweeted this clip of Cristiano Junior dominating in a Juventus Under 9 match:

Italian champions Juventus kick-off their Serie A season with a trip to Parma on Saturday.

Paulo Dybala, who came close to joining Manchester United and Tottenham Hotspur before the transfer window closed, scored the only goal of the game against Triestina with an exquisite turn and chip, although he also missed a penalty.

Aaron Ramsey made his debut after signing from Arsenal during the summer, while new additions Adrien Rabiot and Matthijs De Ligt were also involved.