Renato Sanches
Renato Sanches (right) has been linked with a big-money move to Manchester UnitedGetty Images

Manchester United will reportedly have to pay as much as £45m ($65.1m) to sign Benfica midfielder Renato Sanches. The 18-year-old star is a transfer target of the Red Devils, but the Premier League giants have been told they will need to pay £30m upfront with a further £15m in performance-related bonuses to secure Sanches' services.

The dynamic midfielder is a long-term quarry for United, who have had him watched extensively this season. The Old Trafford club are apparently willing to part with an eye-watering sum of money to sign the highly rated youngster, according to Portuguese newspaper A Bola.

Sanches has burst onto the scene this season, establishing himself as a first-choice player in the Benfica starting eleven. The teenager has also made his debut for the Portuguese national side and is likely to go to this summer's European Championship.

Despite the fee Benfica are demanding, United are said to be close to sealing a deal for Sanches, with £10m being paid for attainable performance-related bonuses and a further £5m for more difficult personal targets. Coincidentally, Sanches shares the same agent as rumoured United managerial transfer target Jose Mourinho, who is an admirer of the player.

Reports have suggested Mourinho will succeed current manager Louis van Gaal at the end of this season, with the Premier League-winning boss thought to be excited about the prospect of replacing the Dutchman at Old Trafford.

Mourinho – who was sacked by Chelsea in December 2015 – will reportedly be given full control over the club's transfer business and is already working on summer targets.