A win would move Sri Lanka level with fourth-placed England on eight points and leave both teams with two matches to play – in the case of the Lankans against West Indies and India.
Already-eliminated South Africa have been dismal in the tournament to date, but won a series in Sri Lanka last year and then claimed a 5-0 clean-sweep at home in March during which the sub-continent side passed 200 in only two of the matches.
The fact that a number of his leading players were either not in South Africa, or were used sparingly in the series, means they will not carry the scars from that mauling, according to Hathurusingha.
"The thing I'm looking at is some of the players that are playing tomorrow were not in South Africa, like Angelo (Mathews), he was not there, and Kusal (Perera) did not play in the last few games … Dimuth (Karunaratne) as well," he said.
"For us, fortunately, most of the top order got some runs somewhere down the line, so hopefully we click as a batting group this game.
"Cricket is funny game. You can lose so many games and win the one that is the most important. I think we have enough talent and skill to compete with them."
Sri Lanka's top score so far has been 247 at the World Cup, though two of their matches have been rained off. They successfully defended just 232 against England last time out.
"We're coming off two wins and a very good victory against England, although we didn't play our best cricket to win the game in terms of batting.
"I think we had a perfect bowling display, defending that target."
With South Africa already out, Hathurusingha admits he is unsure what the intensity of their opponents will be.
"When you have no pressure of qualifying, they can come and play without any pressure, fearless cricket, and that can get them going.
"At the same time they can turn up and just want to go home, so you never know."
Sri Lanka are waiting on the fitness of fast bowler Nuwan Pradeep, who has been unwell.
"He is going to see a doctor today and then I will know in the evening what the situation is with him," Hathurusingha said.
(Reporting by Nick Said; Editing by Toby Davis)
