The Spanish ace has endured a difficult season at Stamford Bridge under Jose Mourinho so far, with the Portuguese coach having deemed him to no longer be a key player for the Blues.
This has led to rumours of a move away from West London, with speculation suggesting that a number of clubs in his homeland are willing to offer him an escape route.
However, United are desperate to land the playmaker.
David Moyes is looking to add some guile and creativity to his ranks in the coming weeks after watching his side make a disappointing start to the campaign.
Despite Chelsea having insisted that their man will not be sold to a domestic rival, United are ready to test their resolve with a £27m offer.
Mata himself is desperate to secure regular playing time in the build-up to the World Cup, and could be tempted by the prospect of becoming one of the Premier League champions’ most important players.
However, a deal may not be achievable unless United allow Wayne Rooney – who was linked with a switch to Stamford Bridge over the summer – to move in the opposite direction.