``We felt that we needed an extra fast bowler to bolster the original side of 15,'' manager Clive Lloyd said.
``South Africa have named 17 which is about right for peace of mind for a series of as many as seven one-day matches.''
Lloyd pointed out that he had been in contact with chief selector Mike Findlay and Board chief executive officer Stephen Camacho explaining the situation and hoped that Dillon would stay on.
Fast bowler Dillon was one of the surprise omissions from the chosen 15. He played in all three matches in the Wills International Cup limited-overs in Bangladesh that preceded the South African tour, earning the Man of the Match award in the semi-final against India when he dismissed Sachin Tendulkar and Mohammed Ahzaruddin cheaply. He is also one of the better outfielders, with a strong throwing arm, in a generally weak fielding team.
Lloyd was realistic in assessing the chances of reversing the 5-0 whitewash in the Test series.
``It's going to be very, very difficult as we're playing against one of the best one-day sides in the world,'' he said.
``We have changed our squad and will be giving a chance to some players who are unknown quantities in that they have played either no one-day internationals or very few.''
Of the four newcomers, all-rounder Keith Semple is yet to play at senior international level, left-arm spinner Neil McGarrell has had one match and fast bowler Reon King two. Of those retained, batsman Daren Ganga has never appeared in a one-day international and Floyd Reifer in only one.
Only Keith Arthurton of the additions has the benefit of experience. The 33-year-old left-handed utility player has 91 one-day internationals on his record.
``It'll be an opportunity to see how the young guys fit in,'' Lloyd said. ``This is the sort of challenge that sometimes brings the best out of you. You just need to look at Ridley Jacobs in his first Test series to see what I mean.''
Lloyd acknowledged that South Africa would ``start off about 20 to 25 runs to the good'' because of the sensational quality of their fielding.
``We don't have guys who have mastered the art of diving around so we've got to sharpen up in that area,'' he said.
``We've also got to look at our extras. We tend to concede too many no-balls and wides in one-day cricket and we've got to concentrate on eliminating them as much as possible.
``But one-day cricket is all about who plays better on the day,'' he added.
``We will go out there knowing that we'll have to play out of our skins to compete but we have top players with good records in this form of the game.''
Lloyd noted that a victory in the opening match, under lights at the Wanderers Stadium here tomorrow, would be a ``tremendous boost to morale''.
``Obviously the guys are pretty down after the defeat in the Test series but they've got to see this as a chance to finish the tour with something to show,'' he said.
``A win first up would be great because winning becomes a habit, just like losing does.''
Curtly Ambrose, who has been retained to spearhead the bowling, has fully recovered from the strained hamstring he sustained during the Fourth Test and that kept him out of the Fifth.
``Curtly is now right as rain,'' team physiotherapist Dennis Waight said yesterday.
``He didn't fancy his chances of lasting five days (in the Fifth Test) so we decided not to risk him as we were already carrying a risk with Courtney (Walsh). But the one-dayers are an entirely different matter. He has a maximum of ten overs and he'll be able to last those.''
The players were given an off-day yesterday after an intensive practice session on Tuesday.
Only captain Brian Lara, who arrived separately from the rest of the team, did not participate in the net session.
``Those who didn't play in the Test have been working out for long sessions each day,'' Lloyd said.
``I can safely say we're ready physically for the grind of one-day cricket over the next couple of weeks.''