Fast bowler Courtney Walsh, who ended the day with 5 for 78, did the early damage before Jacques Kallis (83) and Boucher led the recovery in a seventh-wicket stand of 92. Boucher, who before this match had gone 17 Test innings without a half-century and had scored just 68 runs in the series, faced 183 balls and hit 16 fours.
"I owed it to the boys," Boucher said. "And it was such a great feeling, especially since I only scored my maiden first-class century a few weeks ago on this ground."
Boucher, an excellent cutter and puller of the ball, was helped by some short-pitched bowling by the West Indies which allowed him to indulge in a gem of an innings. However, Boucher also paid tribute to Kallis afterwards: "Jacques is my roommate, and he helped me a lot by his steadiness. When I got past 20, I thought to myself that I wasn't going to throw it away. I hope this makes me more confident, because I can score a few more Test centuries."
At the crease at the close were Allan Donald on 11 and last man Paul Adams on six, the pair surviving the West Indies' star of the day, Courtney Walsh, who finished with five wickets for 78 runs. It was he who finally got rid of Boucher, with an unplayable delivery that the South African could only fend to Brian Lara at first slip having scored precisely 100.
Although they lost two wickets in the session, South Africa clawed their way back to 184 for 6 at tea with Kallis, again proving the pick of the batsmen, undefeated on 72 at the interval. With him was Boucher on 23, looking for the first time in this series like the batsman he promised to be at the beginning of his Test career. Kallis' innings was brilliant at times, but also exhibited the patience which has been lacking from many others throughout the series.
The wickets which fell after lunch went to Walsh, who got Shaun Pollock caught at first slip by Lara for 13, and Mervyn Dillon, who tempted Jonty Rhodes into a rash hook and was caught at mid-on for 24.
South African coach Bob Woolmer was pleased with the batting of Kallis: "He is maturing all the time and he has batted superbly today, as he has for a long time now."
The West Indies struck early, taking four South African wickets for 86 runs in the first session, after captain Lara had won the toss and put South Africa in saying: "I want my fast bowlers to get first go."
Lara's counterpart, South Africa's Hansie Cronje, said he would have chosen to bat.
Lara's faith in his bowlers was immediately justified as Walsh had Gary Kirsten caught down the leg-side by wicketkeeper Ridley Jacobs before Walsh struck again to have Herschelle Gibbs well caught by Floyd Reifer in the slips for two. When Nixon McLean had Daryll Cullinan caught at short-leg for nine, South Africa were in deep trouble at 18 for 3.
Cronje and Jacques Kallis righted the ship with a partnership of 47, before Dillon got Cronje (25) to nibble at one down the leg side, Jacobs taking his second catch. But Boucher was still to come.
First day; West Indies won toss
SOUTH AFRICA first innings
G Kirsten c Jacobs b Walsh 0
H H Gibbs c Reifer b Walsh 2
J H Kallis c Chanderpaul b Hooper 83
D J Cullinan c Wallace b McLean 9
*W J Cronje c Jacobs b Dillon 25
J N Rhodes c King b Dillon 24
S M Pollock c Lara b Walsh 13
M V Boucher c Lara b Walsh 100
L Klusener c Jacobs b Walsh 12
A A Donald not out 11
P R Adams not out 6
Extras (b4, lb3, nb19) 26
Total (for 9) 311
Fall: 1-0 2-5 3-18 4-65 5-98 6-123 7-215 8-270 9-302.
Bowling: Walsh 23-6-78-5 (nb8); McLean 18-1-71-1 (nb6); King 11-1-50- 0 (nb5); Dillon 16-1-62-2; Hooper 17-5-27-1; Chanderpaul 5-1-16-0.
WEST INDIES: D Ganga, P A Wallace, S Chanderpaul, *B C Lara, C L Hooper, F L Reifer, R D Jacobs, N A M McLean, R D King, M Dillon, C A Walsh.
Umpires: R E Koertzen (SA) and S Venkataraghavan (Ind).