Sunderland are in negotiations with Bury for striker James Vaughan.
The 28-year-old striker, who played against Sunderland in Friday night's friendly at Gigg Lane, scored 24 goals for League One Bury last season in 37 appearances for the Shakers.
The club has launched a bid for his services as Grayson looks for another breakthrough in the transfer market following the signings of Everton duo Brendan Galloway and Tyias Browning with winger Aiden McGeady set to follow.
Vaughan has a wealth of experience having played for Everton, Derby County, Leicester City, Crystal Palace, Norwich, Huddersfield and Birmingham City during his career.
The Birmingham-born former Everton trainee is reported to be on boss Simon Grayson's wishlist, the Sunderland boss having signed him for Huddersfield.
The striker stands at 5ft 11ins with Sunderland desperate to add strikers to the squad after the departure of Jermain Defoe, Victor Anichebe and Fabio Borini.
Newcastle United striker Daryl Murphy is also a target, as is Bournemouth's Max Gradel.
Vaughan has caught the attention after netting 24 goals last season and earlier this summer the Gigg Lane outfit rejected a bid for his services from an unnamed club.
Speaking in June, Shakers boss Lee Clark told the Bury Times: "We have had two or three offers for James Vaughan but none have been near our valuation.
"The latest and highest one so far was not a written one, but one over the phone. The bid was in the region of £500,000 but that was nowhere near our valuation.
"We don’t want to let James go but we know everyone has a price and if a bid comes in that we can’t turn down then we have contingency plans in place."