Cristiano Ronaldo shows off black eye in Juventus training

Cristiano Ronaldo shows off his facial injury in training as he looks to end his Serie A goal drought. Getty

Cristiano Ronaldo was all smiles when training with Juventus this week, despite looking like he'd gone a few rounds with Mike Tyson.

The Portuguese star, who has stayed with his club instead of reporting to Portugal during the international break, sported a rather painful black eye as he limbered up and went through the usual drills alongside his Nerazzurri teammates in Turin.

Rather than any extra-curricular boxing activity, Ronaldo suffered the bruise in a collision with Parma defender Simeone Iacopini during Juve's last match.

The 33-year-old has been omitted from the Portugal squad for the international break to allow him to focus on fully recovering his fitness and hopefully arresting his three-game goalless drought at club level.

Ronaldo made his big move from Real Madrid in the summer in search of a new challenge but so far he's found it tough in front of goal, although he seems to be enjoying life in Italy.

Strike partner Mario Mandzukic tweeted a picture on Friday with Ronaldo and his new pals, together with the caption: "WINNING TEAM."

And while that may be strictly true with Juventus enjoying a 100 percent start to the season -- they face Sassuolo next on Sep. 16 (9 a.m. ET, ESPN+) -- we'd wager Ronaldo will be itching to stop his struggles in front of goal.

At least he's firing in training, though. Andrea Barzagli has said he has been astounded by Cristiano Ronaldo's hunger and desire.

"He's scoring all the time in training and I'm sure when he also starts doing so in games, he's not going to stop. He's an incredible professional and it's a pleasure for me to train with him because he transmits energy and great desire to work," he said.

Serie A, you have been warned.