ESPN: Cristiano Ronaldo's Camp Gauge PSG, Real Madrid, Manchester United for Transfer

Cristiano Ronaldo is keeping his options open this summer with Paris Saint-Germain, Real Madrid and Manchester United reportedly among those contacted to "gauge interest in a transfer, according to Rob Dawson of ESPN.

The 36-year-old has one year remaining on his contract at Juventus and is holding talks with the club about his future. He has reportedly already spoken to new manager Massimiliano Allegri.

A move away from Juventus is possible, per Dawson, although the new club would have to match the club's asking price. The Italian club initially spent £105 million to acquire Ronaldo from Real in 2018.

The forward has thrived individually in his three years with the club, scoring 101 goals in 133 matches. He had 36 goals across all competitions this past season.

Ronaldo also helped Juventus win Serie A titles in 2018-19 and 2019-20, although the club dropped to fourth in the table this past season. The team has also struggled in the Champions League, losing in the round of 16 in each of the last two years after a quarterfinal loss in 2019.

The Portuguese superstar could be looking for a new location where he can add to his five Champions League titles. He won four with Real Madrid during his nine years with the team and one with Manchester United, where he spent six seasons earlier in his career.

A return to either of these clubs would likely make them contenders to win the European title in 2021-22.

Real Madrid reached the semifinal this past year before losing to eventual champion Chelsea. Many of his former teammates remain with the club, including Luka Modric, Karim Benzema and Sergio Ramos.

Manchester United lost in the Europa League final on penalties to Villarreal, but qualified for the Champions League after finishing second in the Premier League. He could create an exciting pairing alongside Portugal teammate Bruno Fernandes.

Paris Saint-Germain would be more unfamiliar, but an attack that includes Ronaldo, Neymar and Kylian Mbappe would arguably be the best in the world. It could help PSG finally get over the top after coming close to a UCL title in the past two years.