Cape Town - The form of Quinton de Kock is obviously a major weapon for the Proteas heading into this year's World Cup in England. 

At his destructive best, De Kock is as dangerous as any batsman in world cricket right now. 

That much has been on display in the ongoing ODI series against Sri Lanka, where South Africa's opener has played with purpose and intent in each of his three innings so far. 

A knock of 81 (72) in the 1st ODI was followed by his 94 (70) in the 2nd, and in Sunday's 3rd ODI in Durban De Kock got over the line to three figures with a masterful 121 (108).

The Proteas won all three of those matches and have taken an unassailable 3-0 lead into Wednesday's 4th ODI in Port Elizabeth. 

When De Kock fires how he has been in this series, the Proteas will always be on the front foot. 

Skipper Faf du Plessis knows just how important De Kock is to his side's cause.

"He puts the bowlers under real pressure and when he is on, you can take a team down as a batting unit," Du Plessis explained on Sunday after De Kock's man-of-the-match performance.

"He hits good balls for four. Most batters will wait for a bowler to make a mistake and then hit him to the boundary, but when he is in that mode is he hits you off your good balls and then you bowl bad balls to him.

"Some bowlers fear what he will do to them, so he can almost transform the bowling attack for the rest of the batsmen. It's a real dangerous power and we are very lucky to have him."

Du Plessis is mindful, however, that the Proteas cannot rely too much on their wicketkeeper/batsman to produce the goods time and time again.

"We don't want to rely on one player and we want allow Quinton to play the game that he wants to play," Du Plessis said.

"It's not the way I want us to play as a team. Everyone needs to contribute every single game.

"You're not guaranteed a performance, but you need to be guaranteed of putting in the style of play, the hard work and raising your own intensity."