With just five weeks remaining, hosts Norwich are the ones safe at the moment, but a Sunderland win tomorrow would give the Black Cats a great chance of beating the drop.
The Canaries' resurgent form came to a halt last weekend as they became the first team to lose to Crystal Palace in the league since Christmas, with Jason Puncheon's second-half strike good enough for victory.
Had 17th-placed Norwich won, they would have moved to within a point of Palace above them, but the Eagles have distanced themselves from the relegation scrap and it now looks nailed on that two of Norwich, Sunderland and Newcastle United will join Aston Villa in being relegated.
Alex Neil's side are still in pole position to escape, but with both North-East sides below them having a game in hand and a tough run-in on the cards, Saturday's match is crucial for the Canaries.
A month ago Norwich were in deep trouble having lost eight out of nine and picked up just one point from 27 available, but they have got themselves out of the relegation zone with seven points from their last four matches.
After Saturday's visit of Sunderland they go to Arsenal before back-to-back home games against Manchester United and Norwich. The season then finishes away at Everton exactly a month from today on May 15.
Norwich's improved recent form has been aided by goals from across the team – the Canaries' last 13 Premier League goals have been scored by 10 different players.
At Carrow Road, Neil's men have picked up almost double the points that they have away from home, but they have still only won five of their last 19 Premier League matches there (W5 D5 L9).
Recent form: LLDWWL
Sunderland are now winless in six Premier League matches and have picked up just four points in total in that time (W0 D4 L2), dropping four points behind Norwich in the race to avoid the drop.
Last Sunday they hosted league leaders Leicester City and became the latest team to succumb to Jamie Vardy's season-long party, with the England frontman netting a second-half brace to end Sunderland's run of four straight draws.
The Black Cats have six games left and with their three home matches against Arsenal, Chelsea and Everton, away games at Norwich, Stoke City and Watford might be their best chances of victory in the remaining weeks of the campaign.
However, Sunderland have won just three of their last 27 Premier League away matches (W3 D9 L15) and kept just one clean sheet in their last 17 league matches on the road.
Allardyce will hope that Jermain Defoe, who has scored nine more league goals than any other Sunderland player this season, can find some form and fire the Black Cats to safety.
Recent form: LDDDDL
Both managers have near-fully fit squads to choose from this weekend.
For the visitors, Allardyce has no injuries whatsoever and may welcome back young midfielder Duncan Watmore, who has been out since early February with damaged ankle ligaments.
Norwich are sweating on the fitness of in-form defender Timm Klose, who hobbled out of last week's defeat at Palace and faces a late fitness test before tomorrow's match.
Norwich possible starting lineup:
Ruddy; Wisdom, Martin, Bennett, Olsson; Jarvis, Howson, O'Neil, Brady; Naismith; Mbokan
Sunderland possible starting lineup:
Mannone; Yedlin, Kaboul, Kone, Van Aanholt; Kirchhoff, Cattermole, M'Vila; Khazri, Defoe, Borini
Head To Head
Norwich City have lost none of their last five Barclays Premier League meetings with Sunderland (W3 D2 L0), winning 3-1 at the Stadium of Light on the second weekend of the season.
There has been a red card in three of the last four Premier League meetings between the Black Cats and the Canaries.
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We say: Norwich 1-1 Sunderland
Allardyce has branded this match as must-not-lose, so his side will likely try to frustrate the Canaries and be content with a point.