Rangers won the trio's most recent midfielder battle, bringing Graham Dorrans to Ibrox last summer.
Tony Pulis wants to make Kevin McDonald his first Middlesbrough signing, but Sheffield Wednesday and Glasgow Rangers are also keen on the 29-year-old, the Sun reports on page 50 of its printed edition on Tuesday.
Rangers won the trio's most recent midfielder battle, bringing Graham Dorrans to Ibrox from Norwich City last summer.
A return to either Sheffield - where he spent two seasons with Wednesday's rivals, United - or Scotland - the country of his birth - could appeal to McDonald if offered.
Middlesbrough, though, may also be viewed as an attractive destination, given the club's placing on the outskirts of the Championship play-offs.
The former Dundee, Burnley and Wolverhampton Wanderers player has 18 months left on his Fulham contract.
Could Middlesbrough / Sheffield Wednesday / Rangers land Fulham's McDonald?