José Mourinho is hopeful of making Porto’s Diogo Dalot his first signing of the summer. Manchester United’s manager is targeting the 19-year-old as a long-term successor to Antonio Valencia at right-back.

Dalot has a release clause of €20m (£17.5m) but it is understood this is yet to be triggered by United for a player who made his debut last season, finishing with seven appearances, six of which were in Porto’s triumphant domestic campaign.

Dalot can also play in midfield and at left-back, the position he has operated in primarily for Sérgio Conceição’s side. He completed all of the 0-0 draw at Liverpool in the Champions League last-16 second leg in March as Porto were knocked out 5-0 on aggregate.

Matteo Darmian, who has been a reserve for Mourinho in both full-back slots, is expected to leave, so Dalot is seen as a replacement for the Italian and as a challenger for Valencia’s first-team berth.

The teenager was a member the Portugal Under-16 side who won the European Championship two years ago and the Under-17 team who won the corresponding competition 12 months ago.

Mourinho is monitoring Gareth Bale’s situation at Real Madrid and hopes to sign Shakhtar Donetsk’s Fred as a midfield successor to Michael Carrick, who has retired. He is also interested in Tottenham’s Toby Alderweireld.