Centurion, Dec 28 : Opener Dean Elgar scored a majestic 185 while all-rounder Marco Jansen smashed an unbeaten half-century as the duo pushed South Africa into ascendancy with dominating batting display on day three of first Test against India at SuperSport Park on Thursday. At lunch, South Africa are 392/7 in 100 overs, and have a healthy lead of 147 runs over India. Jansen is unbeaten on 72, his best-ever Test score, in an innings where he mixed sharp driving shots with good judgement to hit nine fours and a six, and has company of Kagiso Rabada, who's at one not out. For India, it was a listless session of lacklustre bowling, inconsistencies in lengths, which allowed Elgar and Jansen to put a stand of 111 runs for the seventh wicket under sunny sky. The listlessness reflected in India's fielding and when the session ended, their body language was deflating and showed lack of enthusiasm. Jasprit Bumrah and Mohammed Siraj produced a few plays and misses in their first six overs, but that was it and Jansen began by capitalising on Prasidh Krishna's poor lines by taking back-to-back fours. Elgar then feasted on Prasidh's bowling by reaching his 150 with a nice drive in the gap between mid-off and extra cover for four off a low full toss, and followed it up with an outside edge running past third slip for four. Jansen struck two fours off Shardul Thakur as there was no end to India's misery, especially after KL Rahul couldn't quickly take the chance of Jansen off Ravichandran Ashwin's bowling. Despite taking the new ball, South Africa continued to take runs quickly as Indian fielders' shoulders continued to drop, as the bowlers couldn't create pressure and weren't able to take wickets. Jansen got his second fifty by chipping Siraj over mid-off and tickled him past fine leg for consecutive boundaries. The duo continued to pick boundaries freely till Elgar was caught down the leg side thanks to Thakur extracting extra bounce on a back of the length delivery. It ended Elgar's innings at 185, his second highest Test score, as the left-handed batter walked off to a standing ovation from his home crowd. India resorted to implementing a short-ball barrage strategy, but it didn't work as Gerald Coetzee tucked Thakur for four, followed by Jansen pulling and tickling for six and four respectively. Coetzee then deposited Prasidh over long-on for six, before picking out mid-off against Ashwin, as the session came to a close, where Elgar and Jansen doubled South Africa's control in the match. Brief Scores: India 245 in 67.4 overs trail South Africa 392/7 in 100 overs (Dean Elgar 185, Marco Jansen 72 not out; Jasprit Bumrah 2-59, Mohammed Siraj 2-90) by 147 runs /IANS