A draw at Manchester City followed by consecutive victories over Chelsea, Cardiff City and Manchester United have carried Gus Poyet's men to the brink of survival, but defeat against West Brom would take their battle for survival down to the wire.
Sunderland currently sit two points clear of Norwich City, who occupy the last remaining relegation spot, and would give themselves an insurmountable advantage with three points this week.
West Brom are not mathematically safe themselves, but even if they did lose at the Stadium of Light, their goal difference is such that it is improbable they would be caught by Norwich.
Sunderland do, however, come into this fixture under the cloud of reports the division's bottom three clubs are taking legal advice over their fielding of striker Ji Dong-Won earlier this season.
The Wearside outfit escaped a Premier League points deduction despite utilising the South Korean forward - set to join Borussia Dortmund in the close season - in four matches without international clearance after his return from a loan spell at Augsburg.
Despite that minor distraction, Poyet is keen to see Sunderland make sure of their survival on Wednesday.
"What we have done in the last four games is unique, incredible," he said following Saturday's 1-0 win at Old Trafford. "A 'miracle' was the word I used a few weeks ago, and apparently every now and again it happens.
"We knew after losing to Everton that realistically we needed to win four of our last six games. We thought we might win all three of our home games, but we also knew we would need a special result in our away games and that would be difficult.
"Well, we managed to get three wins and a draw before our last two games at home, having gone away to Man City, Chelsea and Man United and got a result each time.
"We needed something amazing to happen for us and it’s amazing that we got it.
"Now we are so close and, in front of our fans this week, I want us to finish the job."
The reverse fixture accounted for West Brom's biggest league win of the season so far, with former Sunderland man Stephane Sessegnon opening the scoring in a 3-0 victory.
Ki Sung-Yueng (knee) is sidelined for Sunderland, while long-term absentees Steven Fletcher (ankle) and Carlos Cuellar (hamstring) are also out.
Liam Ridgewell (knee) and Gareth McAuley (groin) could be back in contention for the visitors, but Steven Reid (calf) and Zoltan Gera (hamstring) look set to miss out.
