Hamilton Accies' three-year run in the Scottish Premier League came to an end courtesy of Liam Craig's first-half penalty for victors St Johnstone.
Accies started brightly and had the ball in the net in the first minute, only for striker Nigel Hasselbaink to be judged offside.
But Mark McLaughlin was sent off for a tackle on Saints' Andy Jackson just inside the Accies box on 28 minutes.
And the visitors never recovered from Craig's clinical spot-kick.
With St Mirren winning 1-0 away to Aberdeen, Accies are now six points adrift with one game remaining.
What was always going to be a tough, must-win game for Accies against a side on the verge of losing manager Derek McInnes to English side Brentford was made more so by the loss of their inspirational defender.
Hamilton started brightly and had the ball in the St Johnstone net in the first minute, but Hasselbaink mis-timed his run and was ruled offside.
John Routledge ran on to the end of a perfectly-weighted Dougie Imrie cross from the right wing but headed straight at St Johnstone keeper Peter Enckelman from 18 yards.
St Johnstone picked up their tempo and a magnificently measured pass from 45 yards by Michael Duberry into the Hamilton box was met by Craig, who couldn't quite believe he flouted the chance.
The bright start by Accies started to wane as Saints continued to edge futher into the game.
Hamilton have waved goodbye to the Scottish Premier League
St Johnstone striker Peter MacDonald squandered a chance in front of goal, blasting over the bar from close range after a magnificent run and pass from the left wing by Alan Maybury.
Adams forced another decent save from Tomas Cerny as St Johstone really started to turn the screw.
Hasselbaink attempted to harry the Saints defence with a strike into the bottom right-hand-corner from eighteen yards, but St Johnstone goalkeeper Enckleman was up to the task.
James McAlister added to the efforts of Hasselbaink as he headed goalwards but to no avail for Hamilton.
The turning point of the game came as McLaughlin dragged back Jackson from behind a couple of yards inside the penalty box and received a red card from referee Steve Conroy.
Craig stepped up and struck the penalty hard and low and into the Accies net.
Accies boss Billy Reid decided to make some tactical changes as David Elebert replaced David Buchanan.
Saints' Dave MacKay spun a ball goalwards off the now slippy surface, only for it to deflect clear off the Hamilton defence.
Chris Millar took the wrong option as he elected to have a pop from distance shortly after the break and sent the ball wide of the Accies post by half a yard.
St Johnstone had a great chance to seal Hamilton's fate in the 56th minute when Simon Mensing pulled Peter MacDonald down inside the box.
However, this time Craig's spot kick was saved by Cerny, who guessed right on this occasion and lept bravely and sucessfully to his right.
Jim McAlister had a chance to drag a goal back only for the surface to defeat the Accies midfielder as he miscued a shot.
Imrie flashed a ball from the left across the St Johnstone goal, but there was no-one from Hamilton to capitalise, as news reached McDiarmid Park that relegation rivals St Mirren had taken the lead at Pittodrie.
The same player had a claim for a penalty denied in the 66th minute as Duberry appeared to push the Accies man over in the box, but referee Conroy was not convinced.
Monsoon-like rain greatly influenced the rest of the match and, despite the encouragment from drenched boss Reid, Accies' efforts were not enough to keep the Lanarkshire side in Scotland's top-flight.
Live text and stats
Tuesday, 10 May 2011
(HT 1-0)Hamilton are relegated
Craig (pen) 29
19 Maybury (Invincibile 75)
24 Adams (Reynolds 84)
23 Jackson (May 76)
06 McLaughlin red card
12 Buchanan (Elebert 36)
17 Crawford (Chambers 79)
22 Routledge (Gillepsie 90+2)
07 Imrie yellow card
Ref: ConroyAtt: 2,253
Attempts on target
Attempts off target
90:00+3:50 The referee blows his whistle to end the game.
90:00+1:11 Peter Enckelman takes the free kick.
90:00+1:11 Substitution (Hamilton) makes a substitution, with Grant Gillespie coming on for Jonathon Routledge.
90:00+1:11 Nigel Hasselbaink challenges Michael Duberry unfairly and gives away a free kick.
89:20 Douglas Imrie produces a cross.
87:46 The offside flag is raised against Peter MacDonald. Tomas Cerny takes the free kick.
87:17 Douglas Imrie fouled by Daniele Invincibile, the ref awards a free kick. Free kick crossed right-footed by James Chambers
from left wing, clearance by David MacKay.
85:51 The referee blows for offside against Gary McDonald. Steven Anderson takes the free kick. Free kick awarded for a foul by
Jonathon Routledge on Peter MacDonald. The free kick is swung in right-footed by Chris Millar, clearance by Simon Mensing.
82:55 Chris Millar takes the free kick.
82:55 Substitution Stephen Reynolds replaces Jamie Adams.
82:55 Booking The referee shows Douglas Imrie a yellow card.
82:47 Douglas Imrie challenges Chris Millar unfairly and gives away a free kick.
78:29 Substitution Ali Crawford leaves the field to be replaced by James Chambers.
75:08 Substitution Steve May replaces Andrew Jackson.
74:25 Substitution Alan Maybury leaves the field to be replaced by Daniele Invincibile.
71:39 Inswinging corner taken right-footed by David MacKay, Douglas Imrie makes a clearance.
70:40 Peter MacDonald takes a shot. Save by Tomas Cerny.
70:01 Nigel Hasselbaink takes a shot. Steven Anderson gets a block in.
69:06 Corner taken left-footed by Liam Craig.
67:48 Chris Millar crosses the ball.
66:31 Murray Davidson gives away a free kick for an unfair challenge on Alex Neil. Free kick taken by Alex Neil.
64:36 Douglas Imrie challenges David MacKay unfairly and gives away a free kick. Michael Duberry takes the direct free kick.
64:03 Effort from the edge of the area by Douglas Imrie goes wide of the right-hand post.
63:24 Mishit right-footed shot by Chris Millar. Tomas Cerny makes a save.
61:06 Shot from just outside the box by Nigel Hasselbaink misses to the right of the goal.
57:59 Shot on goal by Andrew Jackson from inside the box goes harmlessly over the target.
57:59 Penalty taken by Liam Craig saved by Tomas Cerny. St Johnstone 1-0 Hamilton.
56:06 Foul by Alex Neil on Peter MacDonald, Penalty awarded.
54:03 Alex Neil concedes a free kick for a foul on Peter MacDonald. Michael Duberry takes the free kick.
50:34 Liam Craig crosses the ball, Jonathon Routledge manages to make a clearance.
48:02 Chris Millar has an effort at goal from just outside the area which goes wide of the left-hand post.
46:36 The official flags Andrew Jackson offside. Alex Neil takes the free kick.
46:05 Free kick awarded for an unfair challenge on Murray Davidson by David Elebert. Peter Enckelman takes the direct free kick.
45:24 Jamie Adams gives away a free kick for an unfair challenge on Nigel Hasselbaink. Free kick crossed by Ali Crawford, Murray
Davidson manages to make a clearance.
45:01 The match restarts for the second half.
45:00+1:09 The half-time whistle blows.
43:53 The assistant referee signals for offside against Douglas Imrie. Free kick taken by Peter Enckelman.
43:32 Ali Crawford fouled by Murray Davidson, the ref awards a free kick. Direct free kick taken by James McAlister.
42:55 Free kick awarded for a foul by James McAlister on Steven Anderson. Steven Anderson takes the free kick.
40:38 Outswinging corner taken by Liam Craig from the left by-line.
35:40 Substitution David Buchanan goes off and David Elebert comes on.
31:48 The ball is delivered by Michael Duberry.
31:33 Chris Millar sends in a cross, Simon Mensing makes a clearance.
28:25 GOAL - Liam Craig:St Johnstone 1 - 0 Hamilton Penalty taken left-footed by Liam Craig and scored. St Johnstone 1-0 Hamilton.
27:29 Sent off The referee sends off Mark McLaughlin for professional foul.
26:55 Foul by Mark McLaughlin on Andrew Jackson, Penalty awarded.
25:38 Inswinging corner taken by Douglas Imrie from the right by-line.
24:18 Inswinging corner taken left-footed by Douglas Imrie played to the near post, Murray Davidson makes a clearance.
24:00+0:06 Outswinging corner taken left-footed by Liam Craig from the left by-line, clearance by Simon Mensing.
22:34 James McAlister has a headed effort at goal from deep inside the area missing to the left of the target.
22:23 The ball is sent over by Douglas Imrie, clearance made by Michael Duberry.
20:54 Nigel Hasselbaink takes a shot. Save made by Peter Enckelman.
18:26 Corner taken by Liam Craig from the right by-line, Jamie Adams takes a shot. Tomas Cerny makes a comfortable save.
18:09 Corner from left by-line taken by Liam Craig.
15:48 The ball is sent over by David MacKay, Mark McLaughlin makes a clearance.
9:05 Peter MacDonald produces a right-footed shot from close range that goes over the bar.
8:14 The ball is crossed by Alan Maybury, save made by Tomas Cerny.
4:58 The ball is delivered by Chris Millar.
4:31 Liam Craig has an effort at goal. Save by Tomas Cerny.
3:47 Peter MacDonald sends in a cross, save made by Tomas Cerny.
3:15 Jonathon Routledge takes a shot. Peter Enckelman makes a save.
0:34 The referee blows for offside. Free kick taken by Peter Enckelman.
0:24 Corner taken by Liam Craig from the left by-line played to the near post.
0:00 The ref blows the whistle to begin the match.
Live text and data provided by The Press Association.
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.