NEW DELHI: Paceman Umesh Yadav admitted India were surprised by South Africa's relentless blocking on Sunday but had no doubts that the hosts will return on Monday to claim the remaining eight wickets to seal a 3-0 win in the four-match series.

Set a 481-run victory target in a series where they have not gone beyond 185 in an innings, South Africa responded with an extraordinary stonewalling at a run-an-over scoring rate to finish the fourth day on 72-2.

Skipper Hashim Amla led by example, taking 46 balls to get off the mark, and remaining unbeaten after making 23 painstaking runs from 207 balls, the slowest innings of 200 balls or more in test cricket.

His partner AB de Villiers, who has scored the fastest 50, 100 and 150 in one-day international cricket, showed another side to his otherwise 360-degree batting.

The right-hander took 33 balls to get off the mark and remained not out on 11 off 91 balls, a knock of exemplary grit.

"It was a surprise. We did not expect them to play like this," Yadav told reporters.

"The way they defended, it was truly a surprise. They were not playing shots and defending every ball, even the ones that could be scored of."

Their dogged defensive approach on a slow pitch made life difficult for the Indian bowlers, Yadav said.

"It becomes more challenging when batsman is not looking to play his shots. It reduces wicket-taking chances.

"This type of cricket gets boring. You send down ball after ball, and nothing happens. They are under pressure and they are naturally blocking to play as long as possible."

Yadav said he and pace colleague Ishant Sharma bowled over the wicket trying to create rough patches for the Indian spinners but that did not click.

The 28-year-old right-arm paceman, however, had no doubts that his team would come up with a new strategy to claim the remaining eight South African wickets.

"It's difficult to bat out the whole day just defending like that. I don't think we should have problem, we have enough time to bowl them out," Yadav said.

"Even today, we created chances. They were lucky as some edges fell in gaps.

"It's not possible that they would bat out an entire day without giving chances. Maybe wicket will turn more tomorrow."