The two sides meet in the Tyne-Wear derby this weekend, a crucial clash for both sides.
The game is looking likely to be key to both sides hopes of avoiding relegation this season, with both currently in the midst of a relegation battle.
Newcastle are 19th in the table and a point from safety, with Sunderland currently occupying 17th place in the table as the season draws to its conclusion.
A win would see the Magpies leapfrog their rivals out of the bottom three, while Sunderland could move further clear if they were to win.
That makes it crucial for both sides, and Clark says it is the biggest of all time.
"If one team loses, it looks as though that team could potentially go down. Hopefully Rafa Benitez has enough time to get his methods across."
The Magpies will certainly be hoping that new manager Rafa Benitez can improve upon what was an encouraging start against Leicester City.
The Foxes may have beaten his side on Monday evening, but there were some encouraging signs from the team during the game.
A big starting point will be sorting out his strike force, who’s struggles this year have been crucial to their team finding themselves in another relegation battle.