Cristiano Ronaldo could have a two-year ban on his hands following his early exit from the Allianz Stadium on Monday, according to former Italy striker Antonio Cassano.

Axar.az reports citing Uksports that the Portuguese superstar walked off the pitch and straight down the tunnel after being substituted in the 55th minute against AC Milan. The forward appeared to shoot a look at manager Maurizio Sarri and mutter something angrily under his breath as he came off.

Cassano – who enjoyed spells at Milan, Inter, Roma and Real Madrid, among others – brought up the possibility when discussing his own similar experience and warned Ronaldo that he could potentially be in violation of anti-doping regulations.

“Did he leave before the end of the game?” Cassano asked on Italian television show Tika-Taka. “You can't do that because there is an anti-doping control.” The 37-year-old likened Ronaldo’s experience to his own when he left the Stadio Olimpico early while representing Roma.

“I had to go back to the stadium urgently to avoid a two-year ban,” said Cassano who opted for an early exit during the match against arch rivals Lazio.