Manchester United are expected to complete the £28.8 million signing of Ander Herrera, the Athletic Bilbao midfielder, in the next 24 hours as Louis van Gaal kick-starts his planned Old Trafford revolution.

After a quiet summer in the transfer market until now, Herrera is on the verge of becoming the fourth most expensive purchase in United’s history and the first in a series of several expected arrivals under Van Gaal.

Although Herrera has only a year left on his contract, United have agreed to meet his €36 million buyout clause since the Spaniard’s price will rocket to €42 million (about £33.7 million) from Tuesday under the terms of his deal.

The cost is still likely to raise some eyebrows given that Herrera is about to