Indian captain KL Rahul praised his group of young players after Sanju Samson hit a maiden international century and set up a series-deciding win for India against South Africa in the third one-day international in Paarl on Thursday.

Samson made 108 in an Indian total of 296 for eight at Boland Park.

South African captain Aiden Markram's decision to send India in to bat on a slow pitch on a hot afternoon backfired as the hosts were bowled out for 218 in reply.

India arrived in South Africa without most of the players who took the country to the World Cup final last month. But they won two of the three matches in convincing fashion.

"It's a really young group of players," Rahul said at the post-match presentation. "They have played a lot of cricket but not at international level.

"The message was to let them adjust to international cricket and let them get used to the pressure. Have fun initially and after a few games start expecting things from them."

Left-arm opening bowler Arshdeep Singh rose to the challenge spectacularly. He took 10 wickets in the series, including four for 30 on Thursday, and was named player of the series.

South Africa were well-placed when Tony de Zorzi (87) and Markram (36) put on 65 for the third wicket to take the total to 141 in the 26th over.

But the innings fell away when Markram gloved an attempted reverse sweep off Washington Sundar to wicketkeeper Rahul and De Zorzi was leg before wicket to Arshdeep 20 runs later.

Former international players in the commentary box were surprised at Markram's decision to bowl first but Markram said he didn't believe it influenced the result.

"We were good in small patches," he said. "I still don't think the surface changed much."

Samson summed up the conditions well, batting patiently as stroke-making became challenging when the two white balls lost their hardness.

Samson and Tilak Varma (52) took 88 balls to post a fifty partnership for the fourth wicket but they picked up the pace and eventually added 116 off 136 balls.

Samson made his runs off 114 balls with six fours and three sixes.

The foundation laid by Samson and Varma enabled India's lower order batsmen to score rapidly towards the end of the innings, with 51 runs scored off the last five overs.