Marvin Zeegelaar has reportedly arrived at Watford's training ground as the defender prepares to join the Hornets.
The Sporting Lisbon full-back has been strongly linked with a £3m move to Vicarage Road over the last 24 hours.
According to Sky Sports News, that deal is close to being completed after the 27-year-old jetted in for a medical.
The Dutchman is contracted to Sporting until the summer of 2019, but the full-back has not represented his Portuguese club this season after being deemed surplus to requirements.
Zeegelaar, who has previously played in England for Blackpool, made 26 appearances in all competitions for Sporting during the 2016-17 campaign.