Multiple reports across Europe have been speculating that Manchester United are now the front row runners to sign Ronaldo from Juventus.
After a summer of transfer speculation, the 36-year-old striker, who will be a free agent next summer, looks likely to stay in Turin.
Juventus are reportedly considering a sensational swaop deal to bring in Mauro Icardi from PSG and sell Cristiano Ronaldo to the French capital.
Allegri was Juventus manager from 2014 to 2019 and won the league title in each of those five campaigns.