Sunderland will reportedly be joined by Liverpool and Tottenham in their pursuit of Vitoria Guimaraes striker Moussa Marega.
Marega, on loan from Porto, has scored 10 goals for Vitoria in eight matches to become the top scorer in the Portugese Primeira Liga.
Stoke City, Watford, Crystal Palace and Leicester City are all also apparently taking a look at the 25-year-old, according to the Sunderland Echo.
The Mali international scored a hat-trick at the weekend against Rio Ave, and his exploits are causing a range of clubs to scout the forward.
The Black Cats are also looking at a move for Ghanaian Frank Acheampong, according to reports in the Italian media. The 23-year-old left-winger is under contract with Belgian side Anderlecht until 2019.
Sunderland have endured their worst ever start to a league campaign, with just two points from their opening 10 league matches.
Manager David Moyes is under serious pressure, as October reaped one point, two goals, three Premier League defeats and an EFL Cup exit at Southampton, during which Moyes was sent to the stands.