South Africa leg-spinner Tabraiz Shamsi lambasted his team's "ridiculous" critics after the Proteas won another T20 World Cup nail-biter to reach the semi-finals.

Shamsi claimed 3-27 in Sunday's three-wicket win over two-time champions West Indies as South Africa chalked up a seventh win in seven games at the tournament.

The 34-year-old took the wickets of dangerous opener Kyle Mayers and top-scoring Roston Chase in his four overs.

Four days earlier, he had conceded 50 runs on the same ground as the United States threatened a shock victory and he was dropped for the victory over England.

"In the previous game I bowled later in the innings and I went for 50 and there were certain critics coming out from the woodwork, speaking about pressure and how I can't handle pressure," said Shamsi.

"I think in a quarter-final match I hope that was enough pressure for me to respond to."

Shamsi said he was dismayed by the criticism he and his team have faced in their campaign.

"It's just a little bit ridiculous when it's ex-players," said Shamsi.

"When they were on the field they did the same things. As cricketers we know sometimes it works, sometimes it doesn't."

South Africa topped their first round group as well as their pool in the second stage Super Eights with defending champions England also going through to the last four.

However, it has been a roller-coaster ride for the Proteas who are still without a world title after a succession of painful near-misses.

At this tournament, they have had to dig deep to preserve their winning momentum.

They defeated the Netherlands by four wickets after being 12-4 at one stage chasing just 104 to win.

A four-run win over Bangladesh followed before they avoided what would have been a seismic shock in a one-run victory over Nepal.

"Obviously most of the games have been a lot closer than we would have personally liked," added Shamsi.

"But the amazing thing is that this new Proteas team always seems to get over the line.

"We've been put under huge pressure basically in every single game that we've played and the boys have managed to find a way to win no matter what the situation, no matter how close the game.

"So that's really pleasing for us as a unit, and in a funny way we're looking forward to it."

For co-hosts West Indies, the exit from their own World Cup was a crushing disappointment.

They had swept through the first round with four wins in four games but lost to England and South Africa in the Super Eights.

"We are disappointed because we think we had the personnel within our room to actually win a home World Cup," admitted captain Rovman Powell.

"Over the last 12 months or so we have played fantastic cricket. It's maybe one of the first times a West Indies team is ranked number 3 in T20 in the world and that must say something."