JOHANNESBURG, Jan 12 (Reuters) - Sri Lanka claimed the wickets of South African openers Stephen Cook and Dean Elgar on the first morning of the third and final test as the home side went to lunch at 79 for two wickets at the Wanderers on Thursday.
Having won the toss and elected to bat on a greenish seamer-friendly wicket, the home batsmen toiled with JP Duminy (23 not out) and a tentative Hashim Amla (six not out), playing in his 100th test, set to resume after the interval.
The tourists got some reward for probing line and length bowling as they seek to avoid a series whitewash.
Cook (10) and Elgar (27) battled their way to 45 after an hour before both fell with South Africa on that score.
Cook was plumb leg before wicket to visiting captain Angelo Mathews in the 16th over, wasting a review on a delivery that was always crashing into the stumps.
Five balls later, Elgar chased a wide delivery from teenage seamer Lahiru Kumara and with little foot movement, edged the ball to Dimuth Karunaratne at first slip.
Duminy and Amla steadied the innings after that, with the former looking particularly fluent as he played a number of excellent straight drives.
A scratchy-looking Amla was dropped at gully by Dhananjaya de Silva off Suranga Lakmal five balls before lunch.
South Africa earlier handed a debut to 24-year-old seamer Duane Olivier, the leading wicket-taker in domestic four-day cricket, in the place of spinner Keshav Maharaj.
All-rounder Wayne Parnell has also come in to replace seamer Kyle Abbott following the latter's decision to take up a Kolpak contract with Hampshire.
Sri Lanka are unchanged with Matthews saying he would have bowled had he won the toss.
The match is a milestone one for Amla, who becomes the eighth South African to mark a century of tests, though it comes at a time when he is battling poor form having scored just 195 runs in his previous five matches.
"He has been the most consistent player, with Jacques Kallis, that South Africa has ever had," South Africa captain Faf du Plessis said in tribute to the 33-year-old.
"I think he has had two lean patches in his career. Although he isn't scoring as many runs at the moment, what he brings off the field still offers a lot." (Reporting By Nick Said; Editing by John O'Brien)