Cristiano Ronaldo has turned to pressotherapy treatment as he strives to return to full fitness with the World Cup just months away.

On February 28, he was forced off during Al-Nassr's 3-1 win over Al-Fahya in the Saudi Pro League.

It was later determined that he had suffered a hamstring injury and there are fears about the severity of the issue.

'After tests, we see the injury suffered by Cristiano Ronaldo was more serious than expected,' Al-Nassr manager Jorge Jesus said on Friday.

'Cristiano will now travel to Spain, like other players who went for treatment when they were injured.

'His injury required treatment in Madrid with his personal therapist, and we hope he returns quickly and helps the team'.

As alluded to by Jesus, Ronaldo is in Madrid undergoing treatment - sharing a picture of himself recently undergoing pressotherapy. It is believed to help with lymphatic drainage by easing swelling, aches and pains as well as detoxifying the body.

The treatment involves using an air pressure machine to inflate a suit that squeezes your arms, legs, or abdomen in a rhythmic motion, similar to a massage. In this case for Ronaldo he is using a leg suit as his post on Instagram on Sunday showed.

Portugal face two friendlies this month, taking on Mexico on March 28 before facing the USA on March 31. It is unclear if Ronaldo will be fit for those matches.

Portugal's captain will hope his participation for the World Cup isn't affected though with his country taking on Colombia, Uzbekistan and another nation to be determined in Group K in June.