Manchester United have agreed a fee with Bologna for striker Joshua Zirkzee, a source has told ESPN.

United have reached a deal worth more than the 40 million ($43m) release clause written into Zirkzee's contract to allow the club to pay the fee over a longer period.

Triggering the release clause would have meant making a payment up front. A source has told ESPN that United have chosen to pay a "modest premium" in exchange for a longer payment period.

Zirkzee, who was also wanted by AC Milan, has already agreed personal terms and will move to Old Trafford on a five-year contract following a medical.

The 23-year-old, who scored 12 goals for Bologna last season, is set to become United's first signing of the summer.

Meanwhile, the club have confirmed Ruud van Nistelrooy and Rene Hake have both signed two-year contracts to become part of Erik ten Hag's backroom staff.

Steve McClaren and Darren Fletcher will stay on as first-team coaches.

Mitchell van der Gaag and Benni McCarthy have left.

"I am delighted that Rene and Ruud have agreed to join our project, adding a wealth of experience, knowledge and new energy to the staff," Ten Hag said.

"Now is a good time to refresh the coaching team as we look to build on the achievements of the past two years and push to the next level."

United announced on Thursday that midfielder Donny van de Beek has left to join Girona. Sources have told ESPN the deal is worth an initial 500k but could rise to 9.1m through add-ons.