The Spanish boss wants a player capable of adding drive and bite to Leeds' midfield, and the 26-year-old has emerged as his top target.
The Whites have seen off stiff competition from promotion rivals Cardiff City, with the Bluebirds reportedly pulling out of a deal for Forshaw following the loan signing of Liverpool midfielder Marko Grujic.
That has opened the door for Leeds United who now look set to secure Forshaw in a deal worth more than £2 million.
Forshaw joins for an undisclosed fee and will go straight into the matchday squad when Leeds host Millwall on Saturday.
"I had a couple of options", said Forshaw.
"Obviously as soon as you get here there is the history and the size of the club and the fan base is huge".
Forshaw becomes United's fifth new signing of the January transfer window, notably following swoops for Belgian left-back Laurens De Bock from Club Brugge and Japan worldwide midfielder Yosuke Ideguchi from Gamba Osaka.
Kalvin Phillips is also just one yellow card away from picking up an automatic two-match ban for receiving ten cautions.
And the club has confirmed that Borthwick-Jackson will return to Old Trafford this month - just five months into his season-long loan move.