Kumar Sangakkara took advantage of an early let-off and batted Sri Lanka into a powerful position with a superb century on the third day of the second Test match against South Africa at Kingsmead on Wednesday. Sangakkara made 101 not out as Sri Lanka, seeking their first Test win of the year - and their first in four tours of South Africa - reached 207 for five at tea, an overall lead of 377. Sangakkara, whose first three innings in the series were 1, 2 and 0, had not added to his overnight score of three when he edged the fourth ball of the morning, from Morne Morkel, towards Graeme Smith at first slip. Wicketkeeper Mark Boucher dived for the ball, obscuring Smith's vision, and the South African captain put down the chance. The left-handed former captain made the home side pay as he constructed a classy innings in overcast and gloomy conditions. Overnight and morning rain delayed the start by an hour and the floodlights were on during most of the day. Sangakkara reached his fifty off 102 balls with four fours and then took command, scoring his second fifty off only 59 deliveries, adding nine more boundaries. It was his 28th Test century. First innings century-maker Thilan Samaraweera shared a 94-run fourth wicket stand with Sangakkara after the first three wickets had fallen for 44 runs to give South Africa hope of bowling themselves back into contention despite trailing by 170 runs on the first innings. Samaraweera made 43 before being deceived by a googly from Imran Tahir which he edged into his stumps. Sri Lanka pressed home their advantage as Sangakkara and new cap Dinesh Chandimal put on an unbeaten 66 for the sixth wicket. Chandimal followed up his first innings 58 with 23 not out. Fast bowling debutant Marchant de Lange, who took seven for 81 in the first innings, claimed the key wicket of Mahela Jayawardene as Sri Lanka struggled early in the day but De Lange was less effective in later spells. Jayawardene had scored 14 when he padded up to De Lange and was given out leg before wicket by umpire Steve Davis. Jayawardene sought a television review but the umpire's decision was upheld when replays showed the ball would have hit his off bail. South Africa lead the three-match series after winning the first Test at Centurion by an innings and 81 runs.