Cristiano Ronaldo makes obscene gesture at fans after they chanted 'Messi, Messi' at him after Al-Nassr's win over Al-Shabab... and could now face an investigation from Saudi FA

Cristiano Ronaldo is reportedly set to face an investigation after appearing to make an obscene gesture following a Saudi Pro League match.

On Sunday the 39-year-old's Al-Nassr took on Al-Shabab, who have a squad that includes the likes of former Atletico Madrid midfielder Yannick Carrasco and ex-Barcelona star Ivan Rakitic.

Ronaldo opened the scoring from the penalty spot on 21 minutes, but his side were pegged back by a spot kick from Carrasco on the brink of half-time.

Talisca restored the visitors' lead following the restart, and the Brazilian was again on hand to secure a late winner for Al Nassr after Carlos equalised for the hosts.

With three points secured by the 3-2 win, Ronaldo congratulated his teammates at the full-time whistle. 

However, the Portugal international appeared to be irked by fans in the crowd chanting the name of his former El Classico rival Lionel Messi.

In response, Ronaldo put his hand to his ear before making a gesture towards his crotch with the signal seemingly aimed at the supporters in attendance.

According to a report from The Telegraph, Saudi newspaper Asharq al-Awsat said the national football federation (SAFF) have since opened an investigation into the incident.

In his second season in Saudi the Portuguese star has maintained his prolific record in front of goal and currently sits top of the league's scoring charts.

Sunday's penalty took his tally for the season to 22 across 20 appearances. 

However, Al-Nassr remain four points behind the undefeated Al-Hilal in the league table.