Faf Du Plessis has branded South Africa's disastrous World Cup campaign as "embarrassing".

The Proteas slipped to a 49-run loss to Pakistan at Lord's that ended any hopes of reaching the semi-finals.

South Africa's worst-ever World Cup could become even more troublesome, with dead rubbers against Sri Lanka and Australia still to come.

But captain Du Plessis insisted he will stand up and be counted in a bid to steer his confidence-shot squad to a positive finish in the tournament.

Asked if this represents the lowest moment of his international career, Du Plessis replied: "Yes, definitely.

"I'm a very proud player and captain, and playing for South Africa means a lot to me. The fact the results we're dishing out at the moment, it's really, really tough.

"It's becoming a little bit embarrassing, we're trying but it's not good enough. Obviously I'm human as well, so it's chipping away at me.

"But I don't have an opportunity to go anywhere, it's important we all front up to this challenge.

"That's when your players need you the most, so I'll stand up to that challenge."

Du Plessis hit 64 in vain as South Africa mustered just 259 for nine, failing to reach the required 309 for victory.

The 34-year-old skipper might be unable to hold onto the captaincy after the tournament, and head coach Ottis Gibson should depart too given his contract is up for renewal.

Du Plessis is determined for South Africa not to slip away with a whimper, but conceded the string of defeats has damaged confidence.

"It's probably harsh to say that was the worst performance ever but we are frustrated," said Du Plessis, whose side have only beaten Afghanistan so far in the tournament.

"We keep making the same mistakes over and over again. Imran Tahir was exceptional once again, but the rest of the guys, it's five out of 10 with the ball, giving the opposition 30 runs too many.

"And then the same again with the bat. We'd get a partnership going then a wicket, build again then a wicket.

"I feel I'm saying the same thing again and again, and that's very frustrating. The guys are playing with low confidence and that means they are making mistakes.

"It chips away at you, trying very hard then coming and playing another game and the same thing happens again.

"It does, it chips away at your confidence, ego, you as a player.

"The frustrating thing for us right now is that we have more people going through lows than highs. So confidence is low."

Pakistan coach Mickey Arthur insisted his side are firmly in the running for a semi-final spot, and hit out at recent social media criticism of his players.

"We're very firmly in the World Cup, we win our next three games we'll qualify, we know that," said Arthur, as Pakistan secured just their second win in six matches.

"When we put our three disciplines together, we'll be exceptional.

"We're alive and kicking without a doubt and if we play our best game we can beat anybody.

"The guys were really hurt by reactions last week, by social media, by a lot of people.

"And hopefully we got a proper reaction from them today that can just shut some people up for a little while."