As reported by the Daily Express, Russian giants Zenit St Petersburg, now managed by former-Spurs boss Andre Villas-Boas, will look to snap up Vertonghen from White Hart Lane at the end of the season if Tottenham miss out on Champions League qualification.
And that frees up Benfica defender Ezequiel Garay, a long-term target for both Zenit and Manchester United, to join the Old Trafford club instead.
Because if Zenit signed Vertonghen, they would have no need to go after Garay. The Argentinian came close to joining the Russian Premier League team in February, but eventually stayed at Benfica citing stability in a title-winning team during a World Cup year as a deciding factor.
But he could be allowed to move on after the tournament, and United are thought to be still tracking his performances in Portugal.
Garay came close to joining United before David Moyes replaced Sir Alex Ferguson, but Moyes may yet rekindle interest in the centre-back in the wake of Nemanja Vidic's departure announcement.
With Rio Ferdinand approaching the end of his United career and Vidic set to join Inter Milan before the start of next season, Moyes needs to add depth to his defensive options.