Sporting CP fullback Pedro Porro is in London for a medical before a 45m euro (39.5m) move to Tottenham.
Porro, who can also play as a wing-back, has three goals and 11 assists in 25 games for Sporting this season.
The 23-year-old Spain international, who has been linked with Spurs throughout the transfer window, was previously at Manchester City, though he did not play for the first team.
Porro joined Sporting from City for 7m last summer after two years on loan.
Although it is being stressed the transfer is not concluded and the structure is complicated, it is anticipated the deal will be complete before the 23:00 GMT deadline.