Durban - The Proteas were caught off guard on day one of the opening Test against Sri Lanka at Kingsmead, says Quinton de Kock.

Largely expected to cruise to victory against a Sri Lankan side that is in administrative turmoil, the Proteas instead fell to 235 all out having been put into bat by their visitors. 

Having been reduced to 17/3 at one stage, South Africa faced an even more disappointing return and would have been skittled for something far more embarrassing were it not for De Kock's 94-ball 80.

Vishwa Fernando (4/62), playing just his fourth Test, and Kasun Rajitha (3/68), playing his fifth, were the chief destroyers for the visitors. 

While opening bowler Suranga Lakmal (1/29) is well-known to the Proteas batsmen, De Kock admitted after the day's play that the hosts were not as well prepared as they would have liked to have been against the other seam threats in the Sri Lankan attack. 

"We didn't think we were going to get off to such a bad start, but credit to them. They bowled well up front," De Kock said after notching up his 15th Test half-century. 

"We've understood that Suranga Lakmal is a serious opening bowler, but we were a bit unaware of the new guys.

"They caught us off guard, so going forward we will plan better and I think we'll get off to better starts.

"The two new guys, we have only played against one of them in white ball cricket and otherwise we haven't seen them before. It can become quite tough, especially with the pitch. They made us work hard for what we got.

"Those two are solid bowlers and they will give us trouble throughout the series."

While De Kock acknowledged that South Africa had not scored enough runs, he backed their own variety of seamers to get the job done on Thursday. 

"I think we're a little bit under par. We were hoping for a better score, but unfortunately they bowled well and hit their areas. We were a few runs short," he said.

"We've got Dale, Vern, KG and Duanne who all bring different attributes to our attack, so I'm sure one of them will find a way to get on top of the Sri Lankan batsmen."

Play on day two will start at 10:00.