Tabraiz Shamsi was "relieved" as his heroics helped South Africa edge to a one-run victory over Nepal at the T20 World Cup in Kingstown.

Nepal looked on the verge of a shock victory, needing two from the final ball to secure the win. However, Ghulsan Jha was run out at the non-striker's end as South Africa came through unscathed to make it four wins from four at the tournament.

Despite Ottniel Baartman bowling the final over, it was Shamsi's 4-19 that proved crucial in South Africa getting over the line, including two wickets in the 18th over to turn the game back in his team's favour.

The spinner was thankful South Africa avoided an unlikely defeat, telling reporters: "[I am] definitely relieved.

"The team is standing up to the pressure and that's great to see."

Proteas captain Aiden Markram praised the efforts of Nepal, whose narrow defeat means they are eliminated from the competition with one game to spare in Group D.

"You have to give Nepal a lot of credit," Markram said. "Throughout the game they put us under a lot of pressure, and it shows the quality they have."

While Nepal skipper Rohit Paudel was disappointed in the defeat, he also took pride in how his team fared against one of the tournament favourites.

"I'm very proud of the unit, the way we bowled and batted," Paudel stated. "We were very close but a little far."

Nepal came to within two runs of a famous victory over South Africa as the Proteas edged a thrilling encounter in Kingstown to remain unbeaten at the T20 World Cup. 

Sompal Kami knew that two runs from the final ball of the match would secure an unlikely triumph, but batting partner Ghulsan Jha was run out at the non-striker's end to conclude their first meeting in international cricket. 

South Africa were restricted to 115-7 with opener Reeza Hendricks producing 43 runs from 49 balls, ultimately handing the initiative to their opponents to keep their Super 8s hopes alive.

Nepal would last until the eighth over before losing Kushal Bhurtel and Rohit Paudel in three balls, but the Rhinos would steady the ship, leading to a nail-biting finish. 

However, Tabraiz Shamsi (4-19) struck twice in a game-changing 18th over, aided by Ottniel Baartman denying seven runs in the final over to decide the tie. 

South Africa face the United States in Antigua on June 19, while Nepal search for their first win of the tournament as they take on Bangladesh in their final Group D game.

Meanwhile, New Zealand secured their first win of their T20 World Cup campaign with relative ease, beating Uganda by nine wickets at the Brian Lara Cricket Academy.

The Black Caps exit from the tournament had already been confirmed following Afghanistan's seven-wicket triumph over Papua New Guinea, exiting a World Cup before the last four for the first time since 2014.

Trent Boult dictated the early pace of the encounter, taking two wickets inside the first over as their opponents quickly saw five wickets fall for just 15 runs.

Kenneth Waiswa was the only batter for the Cricket Cranes to reach double figures, as wickets from Tim Southee (3-4) and Mitchell Santer (2-8) in successive balls saw Uganda all out for 40. 

Kane Williamson's side faced just 33 balls on their way to victory, as Devon Conway scored an unbeaten 22 from 15 balls to win the contest ahead of their final Group C fixture against the Barramundis.