Manchester United and Arsenal are leading the race to sign Benfica winger Andrija Zivkovic.
The Serbian international, who has a £52.5 million release clause in his contract, is one of the hottest properties in European football.
Monaco, Ajax and Leicester City have also sent scouts to watch Zivkovic in recent weeks, while both Valencia and Sevilla have previously been linked with the player.
Zivkovic progressed through the Partizan Belgrade youth system, before making his senior debut in April 2013.
He signed his first professional contract with Partizan in August that year and went on to captain the club the following April.
Zivkovic signed a five-year deal with Benfica in July 2016. He had scored 24 goals in 93 appearances for Partizan.
He has represented Serbia at both junior and senior level and has been widely tipped to secure a big money move this summer.
The diminutive winger has scored four goals and created 16 more in 45 appearances in all competitions for Benfica.