The depleted tourists, on the other hand, appear to have worked out the combination that will take the field at the Sinhalese sports club under their first black captain Ashwell Prince.
The contrasting mood in the rival camps is unexpected. The South Africans were the ones in trouble in the absence of three top stars in regular captain Graeme Smith and leading all-rounders Jacques Kallis and Shaun Pollock.
Sri Lanka are, however, anything but settled despite their successful tour of England recently where they fought back to draw the Test series 1-1 and blanked the hosts 5-0 in the One-dayers.
The hosts must decide if Jayasuriya, 37, should play in the middle-order or risk sending him as opener at the expense of the younger Michael Vandort to accommodate a fifth bowler.
Jayasuriya was controversially brought out of Test retirement by the new chief selector Asantha de Mel in May and rushed to England as an additional member of the side.
The left-hander was ignored for the first two Tests by the team management, but played in the third at Nottingham in the middle order and scored four runs in each innings.
Jayasuriya, Sri Lanka's most successful Test batsman with 6,621 runs in 103 matches, has not scored a half-century in his last 15 innings even though he makes runs regularly in one-day cricket.
Coach Tom Moody would not reveal Jayasuriya's likely batting position in the first Test but media reports said the selectors wanted the veteran to return as opener to partner young Upul Tharanga.
South Africa, meanwhile, are confident of putting up a good fight even though Smith and Kallis are recovering at home from injuries and Pollock is not available for the first Test following the birth of his second child.
Jacques Rudolph, a late replacement for Smith, hit form with 157 and 58 in the three-day tour opener against Sri Lanka's 'A' team, while Hashim Amla made 150.
With Prince and A.B. De Villiers scoring half-centuries, South Africa's only worry is the form of openers Herschelle Gibbs (one and 10) and Boeta Dippenaar (one and 25).
Coach Mickey Arthur was, however optimistic of a good showing from both openers, including Gibbs, who returns to the side after being dropped from the home series against New Zealand due to bad form.
"I am not worried," he said. "It's only a matter of time before they turn a good start into big innings."
Fast bowler Makhaya Ntini, who spearheads the bowling in Pollock's absence, worked up tidy pace in the warm-up match while fellow paceman Andre Nel claimed 4-39 in the first innings.
South Africa, who lost both the Test and one-day series on their last tour of Sri Lanka in 2004, understandably regard off-spinner Muttiah Muralitharan as the major threat in the two Tests.
The off-spinner, whose 635 Test wickets are bettered only by Australian record-holder Shane Warne's 685, has taken 47 wickets in seven home games against South Africa.
"Murali is obviously our main worry," said Prince of the bowler who has claimed an astonishing 180 wickets in his last 25 Test matches.
"We've got a lot of footage and we will be analysing how best to combat him."
The second Test will be played at the Sara stadium here from August 4, followed by a tri-series also featuring India from August 14-29.