Manchester United manager Louis van Gaal has refused to rule out making a bid for Roma midfielder Kevin Strootman.
Juventus are confident Arturo Vidal will not be lured away by Manchester United in the summer transfer window.
On a chaotic evening, United's official photographer has arrived at the AON Training Complex as the club doctor has left it.
Both moves seem significant given Marouane Fellaini has apparently handed in a transfer request at Everton as they could allow the doctor to oversee a medical before heading back with the Belgian for his official confirmation as a United player.
Herrera remains in Bilbao though.
Reports in Spain have suggested United have agreed to meet a 36million euro clause in the midfielder's contract and have also agreed a five-year deal for Herrera.
However, whilst club officials visited La Liga headquarters this evening in order to conclude the paperwork, they apparently hit an unexpected snag and left without completing the deal.
With time ticking down to the transfer window closing, United may have a problem pushing through the deal.
What they do have though is a little bit of wriggle room afforded to clubs who have a transfer agreement in principle without actually finalising it.
Under such circumstances, providing the Premier League receive a Deal Sheet at some point between 9pm and 11pm BST this evening, containing signatures from both clubs and the player, United will be granted an additional hour to complete the transfer.
In that time, all loose ends must be completed to comply with FIFA's international transfer matching system to allow the deal to be ratified.
As it is virtually unknown for the world governing body to extend the time limit for these transfers beyond midnight, if United have not finalised the paperwork by that time, they will have to walk away from what would be the second biggest incoming transfer in their history.