Chad le Clos (Getty)
Cape Town - Bookmakers suggest Chad le Clos will suffer a second defeat in a butterfly final in Rio to swimming superstar Michael Phelps.
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Leading bookies Sportingbet have installed Phelps as a 8/15 firm favourite to defend his title in the 100m butterfly.
Le Clos is on offer at 11/5 with Hungary's Laszlo Cseh at 6/1.
Phelps stormed to victory in the 200m butterfly on Tuesday night (Wednesday morning SA time), denying Le Clos a repeat of his London victory.
Le Clos ended up outside the medals in a disappointing fourth place.
Phelps will begin the defence of his 100m title in Lane 4 in the sixth and final heat on Thursday at 19:31 (SA time).
Le Clos will swim out of the same lane in the previous heat (19:28 SA time).
The final of the 100m butterfly is scheduled for Saturday at 03:12 (SA time).
The men's 100m butterfly also represents the last realistic chance Team SA have at a medal in the pool in Rio.
The men's 4x100 medley relay is the last event SA will enter a participant or team, but they will face stiff opposition from the likes of favourites, the USA, Australia and Great Britain in particular.