South Africa begin their Champions Trophy challenge at the Oval on Saturday by taking on a Sri Lanka side against whom they have already enjoyed overwhelming one-day international success this year.
The Proteas whitewashed Sri Lanka 5-0 in a bilateral series in South Africa in January.
Sri Lanka were not alone in being a touring side routed in 50-over cricket by South Africa, with the Proteas previously also hammering Australia 5-0.
Yet for all they are top of the one-day international rankings, South Africa have a reputation for under-performing in International Cricket Council tournaments.
The only ICC event they have won was the inaugural Champions Trophy in 1998.
South Africa also boast the world's number one-ranked ODI batsman and bowler in AB de Villiers and Kagiso Rabada respectively.
In all they have four batsmen and two bowlers in the respective top 10 ICC rankings, while seventh-placed Sri Lanka have none in either list.
"We're still ranked the No 1 team in the world going into the tournament, so there are quite a few reasons for us to be confident," said South Africa ODI captain de Villiers, whose side were beaten 2-1 away to Champions Trophy hosts England in a preceding three-match warm-up series.
"But we're still humble at the same time and know that we have to work hard and take it one step at a time to win this," he added.
Sri Lanka head into the tournament as underdogs and one of the key reasons they've struggled in recent months has been the absence of fast bowler Lasith Malinga, who hasn't played any ODI cricket since November 2015 due to a knee injury.
The return of Malinga, whose unorthodox, slingshot action makes him one of the most difficult bowlers to face in world cricket, would be a massive boost for Sri Lanka.
"He has been our leading bowler for many years and we missed him," said captain Angelo Mathews.
"He is very keen to return to ODI cricket and we are looking forward to him performing again."
There are also question marks about all-rounder Mathews's availability for the South Africa match after scans revealed he'd suffered a calf strain.
He didn't play in Sri Lanka's warm-up game against New Zealand and will go through a fitness test on Friday.
Sri Lanka's form ahead of the competition has been mediocre, given they have lost warm-up games to Australia, New Zealand and even Scotland.
They believe batting against spin bowling is South Africa's weakness, however, and will look up to left-arm wrist spinner Lakshan Sandakan to give them the edge.
The 25-year-old has played only six ODIs and the Sri Lankans believe his variety will trouble their opponents.
Sri Lanka arrived in England well in advance of the Champions Trophy to acclimatize to the conditions and conducted a week long residential camp in Kent.
Now they will hope that work pays dividends at the Oval, the south London headquarters of Surrey -- a county for whom retired Sri Lanka great Kumar Sangakkara has been in prolific form this season, with five successive first-class hundreds.