Sri Lanka head coach Sanath Jayasuriya has expressed disappointment over his team's inability to capitalise on key moments during their 109-run defeat against South Africa in the second Test at St. George's Park, Gqeberha.

South Africa completed a 2-0 series sweep to deal a blow to Sri Lanka's hopes of securing a spot in the ICC World Test Championship final.

South Africa's victory was spearheaded by spinner Keshav Maharaj, who claimed five wickets for 76 runs, wrapping up the Sri Lankan innings for 238 within 70 minutes on the final day. Despite being set up for an intense finale with both teams vying to keep their World Test Championship aspirations alive, Sri Lanka faltered under pressure.

Jayasuriya pointed at the failure of Sri Lankan batters to convert starts into significant scores as a critical factor in the defeat. In the first innings, all of Sri Lanka's top five batters managed to reach at least 20, yet only Pathum Nissanka went beyond 50. Even Nissanka, who made a half-century, was unable to capitalize on his start.

SA vs SL, 2nd Test: Highlights | Scorecard

"Batsmen have to convert their scores into hundreds - 30s and 40s aren't enough," Jayasuriya lamented. "On challenging wickets like these, at least two batters need to score centuries. We didn't get that this time. All we managed were two 80s, which isn't sufficient at this level."

The series was particularly tough for Kamindu Mendis, whose average plummeted from 91.27 before the series to 74 by its conclusion. Despite the dip, Jayasuriya defended the young batter, emphasizing his potential and confidence.

"Kamindu is a quality player," Jayasuriya said. "Every player has their tough series, and this was his. He remains a positive presence, and I'm confident he'll bounce back stronger."

Jayasuriya highlighted specific periods during the Test where Sri Lanka let their grip slip, starting with the second morning, when South Africa's lower-order partnerships added 89 crucial runs.

"In that first innings, we allowed roughly 40 runs too many after getting eight or nine wickets," he noted.

The third morning proved equally costly as Sri Lanka collapsed, losing five wickets and missing the opportunity to secure a substantial first-innings lead.

"In the second innings, their tail adding 25-30 extra runs hurt us," Jayasuriya said. "And losing two quick wickets in the evening session when we were 117 for 3 made our job even harder."

Despite the setbacks, Jayasuriya praised the efforts of senior players and stressed the importance of learning from such losses. He reiterated his belief in the team's ability to play "positive cricket" and take lessons from the defeat as they prepare for future challenges.

South Africa's Kyle Verreynne and Keshav Maharaj were standout performers in the match, with Verreynne's brisk century setting the tone on the second day. For Sri Lanka, the focus now shifts to addressing shortcomings and regaining momentum as they aim to keep their World Test Championship hopes alive.

"We need to sharpen up in critical moments," Jayasuriya concluded. "If we can do that, we'll be able to compete better against strong sides like South Africa."