Remarkably, London (12th), Hull KR (11th), Huddersfield Giants (tenth) and Wakefield Trinity (ninth) are all locked on 20 points.
Broncos captain Jay Pitts scored a 78th-minute try to gain his elated side the victory they needed last night to avoid being almost certainly condemned to relegation.
Stunned Rovers – who came back from 12-0 down to lead – would have made sure of their safety with success but are now left still fearing for survival after the sobering 20-16 defeat.
Other results on Friday saw the incredible final shoot-out come into play – Wakefield losing 23-16 at Warrington Wolves and Huddersfield being thrashed 48-6 by leaders St Helens.
Spirited London – promoted last autumn and given little chance of survival outside of their own camp – were supposed to play at Wakefield next Sunday when KR were also due to be in action at Salford Red Devils.
However, all four clubs under threat will now play on Friday evening and kick-off at the same time (7.45pm).
Wakfield host Broncos at Belle Vue in a game that has been selected for broadcast by Sky Sports, Rovers head to a Salford side who are on a seven-game winning run after Friday night’s 20-12 victory at Leeds Rhinos and Huddersfield entertain a Catalans Dragons side who remain in freefall following a 46-12 thrashing at Wigan Warriors.
The winners of Wakefield and London will be safe come what may, while Hull KR and Huddersfield know victory will see them home regardless of other results. But for any side that loses their fate could come down to points difference.
As it stands, Wakefield (-124) are best off in that regard followed by Huddersfield (-207), Rovers (-219) and, lastly, London (-273) who remain bottom.
Sky Sports have confirmed that Wigan Warriors v Castleford Tigers will be Thursday night’s live TV game (7.45pm) with Daryl Powell’s team looking for the win that will secure the fifth and final play-off place.
Leeds Rhinos versus Warrington and Hull FC against St Helens will take place on Friday.
Round 29 confirmed fixtures, Thursday, September 12: Wigan Warriors v Castleford Tigers (7.45pm). Friday, September 13 (7.45pm): Huddersfield Giants v Catalans Dragons, Salford Red Devils v Hull KR, Wakefield Trinity v London Broncos (on Sky Sports).