Montgomerie was told by the tournament director, John Paramor, that he had been fined pounds 100 for swearing at the end of his second round, and then shot 77 to finish the event alongside Sam Torrance on the 12-over-par total of 296.
Couples, three strokes behind with only two holes to play, won the substantial first prize with a 10ft birdie putt at the second extra hole after forcing his way into a play-off with Loren Roberts, his American Ryder Cup team- mate, and Fiji's Vijay Singh.
The trio had tied on the five-under-par aggregate of 279 after Couples holed a 25-foot eagle putt on the 17th and another from the same distance for birdie on the last. It gave him a closing 71, while Singh shot 70 and Roberts 69.
Couples, inaugural winner of the title in 1991, came nearest at the first play-off hole - they returned to the 18th tee each time - but his 18ft putt stopped on the lip. With a pounds 195,000 prize differential at stake, all three set up birdie chances next time, but after Roberts failed from 15 feet, Couples made his and Singh missed from six feet.
Montgomerie was heading for a round in the 80s until he also finished eagle-birdie, pitching into the hole from 40 yards at the last after pulling his approach up against the spectator stand.
His worst round of 1995 was his opening 79 in the Million Dollar Challenge in Sun City a fortnight ago - he was 11th out of 12 there - but he said: "Not too much should be read into it. I'm just tired."
In comparison with John Daly, Montgomerie's was still a fine performance. The Open champion shot 80-80-84-80 for a humiliating 40-over-par aggregate of 324, the worst in the event's history by 13 strokes.
Daly, who arrived on the eve of the event and spent little time practising range all week, looked like breaking 80 for the first time until he double- bogeyed the 13th, bogeyed the long 14th and then ran up an eight at the 175-yard 15th. His tee shot there finished against a wall; his second was an air shot; and the third sent the ball into water. He was round in a mere 135 minutes.
Daly's one previous appearance in the world championship in 1991 saw him shoot 77-87, and then get disqualified for signing for a wrong score. He was still paid pounds 35,000 for that, so for six rounds, totalling 62 over par, he has received more than pounds 70,000.
Nick Faldo partnered Montgomerie in their final 18 holes of the season and ended a frustrating year on the course and a traumatic one off it with a 68 to take joint ninth place.
n Sweden's Anders Forsbrand withdrew after going down with early signs of pneumonia. He was taken to hospital with a temperature of 103F but was eventually allowed to return to his hotel.
JOHNNIE WALKER WORLD CHAMPIONSHIP (Montego Bay, Jamaica) Final scores (US unless stated): 279 F Couples (US) 70 67 71 71; L Roberts (US) 70 70 70 69; V Singh (Fiji) 69 68 72 70 (Couples won at 2nd extra hole). 285 B Langer (Ger) 71 73 73 68; M Calcavecchia (US) 72 70 70 73. 288 P Mickelson (US) 72 72 72 72; W Riley (Aus) 66 71 76 75; A Cejka (Ger) 73 75 65 75. 289 N Faldo (GB) 74 75 72 68; E Els (SA) 79 73 66 71. 290 P Senior (Aus) 77 70 71 72; P Azinger (US) 75 74 68 73. 291 L Janzen (US) 75 73 74 69. 292 B Mayfair (US) 75 73 68 76. 293 D Duval (US) 72 77 70 74. 296 C Montgomerie (GB) 75 72 72 77; S Torrance (GB) 77 75 67 77. 301 T Izawa (Japan) 80 71 72 78. 324 J Daly (US) 80 80 84 80. Withdrew: A Forsbrand (Swe).Reuse content