Mohammad Amir the big threat for struggling Proteas

The Proteas paid the price for their shortcomings with the bat once again at Edgbaston on Wednesday, losing by four wickets to New Zealand after posting just 241-6.

Mohammad Amir in action against India in Manchester on June 16.   -  AFP

Pakistan paceman Mohammad Amir should be rubbing his hands together at the prospect of capitalising on South Africa's batting frailties in a must-win Cricket World Cup clash at Lord's on Sunday.

The Proteas paid the price for their shortcomings with the bat once again at Edgbaston on Wednesday, losing by four wickets to New Zealand after posting just 241-6.

Although South Africa was poor in the field, lack of runs was also their downfall and Kane Williamson showed them how it is done with a match-winning unbeaten century.

Faf du Plessis' side will have to raise their game in the first match of the tournament at Lord's, where Amir will look to add to his impressive tally of 13 wickets at an average of 13.

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Imran Tahir is just two strikes shy of Allan Donald's record tally of 38 World Cup wickets for South Africa and the spinner — who has not yet been hit for a six in the tournament — could have a big role to play.

Neither side has any margin for error, with just one win apiece leaving them highly unlikely to feature in the semifinals.

Pakistan has lost seven of its 11 ODI games at the famous London venue, while the Proteas have been beaten in three of their four matches at Lord's in the 50-over format.

South Africa could take heart from the fact that it has won three of four World Cup encounters with the ICC Champions Trophy holders.

They have also come out on top in three of their previous four ODI encounters with Pakistan and it may only be pride on the line as they eye another.