Crystal Palace are attempting to scupper Porto's move for Hull City coach Marco Silva, sources close to the London club have told ESPN FC.
Silva is set to confirm his departure from Hull after triggering a break clause in his contract following their relegation from the Premier League.
He is in demand both in England and overseas after impressing at Hull after his arrival at the club in January.
Porto were in pole position to land Silva after holding talks with him earlier this week about replacing Nuno Espirito Santo, who stepped down from his role on Monday.