Summer time and the start is easy. Or so it would seem for South Africa.

The season proper kicks off on Sunday with a fixture against Ireland, a team South Africa have played only four times in the past and beaten on every occasion. What could possibly go wrong? Faf du Plessis, the stand-in captain, knows what.

"When you play a small nation, you've got everything to lose and they've got everything to gain," he said. "They can play the perfect match and if you make a couple of mistakes, they beat you and that's never something you want to do as a big nation."

Without regular captain AB de Villiers, who is injured, regular opener Hashim Amla, who is awaiting the birth of his third child, and regulars in the bowling attack like Dale Steyn, Morne Morkel and Kyle Abbott, South Africa could be vulnerable. This means they may take the field with three debutants. They will definitely have one in Temba Bavuma, who has been asked to open the batting as South Africa look to develop him in that role for the future.

Not only is it a position that is fairly unknown to him, but it is also a format he has not exactly set the stage alight in. Across 69 List A matches, Bavuma has an average of 26.73, so there will be pressure on him to perform. "It's a great opportunity for him," du Plessis said. "He will be the first guy to say that his one-day record is not what he wants it to be, so he has got an opportunity to improve it."

The other rookies, Dwaine Pretorius and Andile Phehlukwayo, make up two of three allrounders in the squad alongside Wayne Parnell. Had Chris Morris been fit, South Africa would have had a quartet of two-in-one players to choose from - a luxury after several years of searching for someone to fill that spot.

Having tried several players, including Ryan McLaren and Albie Morkel, South Africa have been unable to find a top-order allrounder in the Jacques Kallis mould. They now seem to be settling with the idea of a seam bowler who can bat in the lower-middle order. Now, it up to Pretorius, Phelukwayo and Parnell to prove their worth. "We've always said that we really need allrounders to come through to make the balance of our team easier," du Plessis said. "They will all get game-time over these ODIs."

The main worry for South Africa is not who will get time in the middle, but who will not. Morkel and Morris will not feature at all as they recover from back and knee niggles respectively, but the focus is on de Villiers, who will undergo a fitness test on Tuesday to determine whether he needs surgery on his elbow. If he does, he will miss the Test tour of Australia, which will leave it to du Plessis to lead, and it seems he is more than willing to take over in any format.

Du Plessis, who took over for the two-Test series against New Zealand last month, believes he is improving in the job.

"Captaining in a Test match was unbelievable," he said. "That is the pinnacle To get through that series with a much-needed win, which we needed as a team, also gave me as a captain confidence. As a captain you need to learn always, you are never the finished article. I enjoy making sure the team is going in the right direction and leading by example."

Firdose Moonda is ESPNcricinfo's South Africa correspondent