Sanju Samson smashed his first international century as India beat South Africa by 78 runs to clinch the three-match One Day International series 2-1 at the Boland Park in Paarl on Thursday.

Samson (108) and Tilak Varma (52) stitched together a 106-run stand after India were reduced to 101-3 with opener Sai Sudharsan, debutant Rajat Patidar, and skipper KL Rahul back in the hut well before the 20th over.

Promoted to No 3 for the contest, Samson held his own along with Varma to anchor the Indian innings in the middle overs, where run scoring was made tough by a slow surface and accurate bowling from Keshav Maharaj and Aiden Markram.

After having added 59 runs in the opening ten overs, India only managed to add 73 in the next 20 as South Africa brilliantly strangulated the run flow. But the ten-over phase from 31st to 40th over saw Samson and Varma getting into the their own with frequent boundaries to keep India afloat in the series decider.

Once Varma fell soon after his half-century to Maharaj in the 43rd over, the ever reliable Rinku Singh (38) provided the much needed impetus with big shots. Washington Sundar, who came into the side in place of Kuldeep Yadav, also scored a valuable 14 as India notched up a total of 296-8 in their quota of 50 overs.

Chasing a tricky total, South Africa lost opener Reeza Hendricks and Rassie van der Dussen early. But Tony de Zorzi, the centurion from the previous match, continued to impress as he scored an 87-ball 81 to keep the hosts alive in the chase.

Zorzi smashed six boundaries and four sixes before Arshdeep Singh returned to prize him out in the 30th over of the innings, after having already accounted for Hendricks early on.

India were also bouyed by some tight bowling from Sundar (2/38) and Axar Patel (1/48) even as Arshdeep finished with 4 wickets for just 30 runs in nine overs.

South Africa were eventually bowled out for just 218 with just over four overs to spare to hand India a series win.