Manchester United chief executive Ed Woodward believes the Premier League champions will make wholesale changes to their squad in the summer.
The Red Devils are currently languishing in seventh spot in the Premier League - having failed to replicate the kind of form that saw them crowned champions last season.
Manchester United manager David Moyes has been under severe pressure throughout the course of the season - due to the fact that the north-west are out of the FA Cup, Capital One Cup and nine points off of a Champions League spot.
The former Everton boss signed Mata in hope that he could help them seal a place in next season's Champions League, however Manchester United have dropped points in two of the games he has played.
And Woodward has suggested Manchester United will continue to splash in the summer by targeting the world's best players.
Speaking at the announcement of Manchester United's record second-quarter revenue of £122.9million, Woodward said: "It's fair to say we are focused on strengthening the squad we are looking at some players in the squad who we would perhaps look to sell this summer.
"We wouldn't necessarily look to churn a significant number of players, because that can have a destabilising effect.
"Historically we have done three sales and three purchases each year [on average] and it's possible we would do more than that [this summer]."
Woodward - like Moyes - has a point to prove this summer as the chief executive, who replaced David Gill at the end of last season, failed to complete deals for several Manchester United targets.