Australia continued to ride on captain Michael Clarke's 27th test century on day two of the third and decisive test against South Africa, going to an early tea on 494-7.
Clarke was unbeaten on 161 on Sunday when rain swept in at Newlands to hold up Australia's progress.
Although South Africa enjoyed a better second session as JP Duminy took three wickets to achieve career-best figures of 4-73, the tourists maintained a strong hold on the match thanks to Clarke's dominance.
South Africa was hindered by the continued unavailability of fast bowler Dale Steyn, who failed to overcome a hamstring strain picked up on the opening day. With low cloud around Newlands at the start of the day and a second new ball in hand, that was a major blow for the hosts, who failed to make early inroads.
Clarke began the day on 92 not out but spent 25 deliveries on 99 before driving Vernon Philander's delivery through the covers for four to go to three figures.
The Newlands crowd gave the Australian captain a rousing ovation, having seen him get hit on the elbow, jaw, shoulder and hand during a brutal spell from Morkel on Saturday.
While Clarke was struggling to find his 100th run, Steve Smith was having no trouble scoring. He drove Philander back over his head for six, and then slashed Morkel over extra cover for another maximum.
Such brilliance made his lapse in concentration against part-time spinner Dean Elgar all the more disappointing, as he chopped a wide delivery onto his stumps to depart for 84.
Shane Watson then scored a quick 40 either side of lunch before holing out to long-off Duminy, who went on to pick up the wickets of Brad Haddin and Mitchell Johnson with consecutive deliveries.
However with the dismissals coming off the last two balls of the over, Duminy was left with a long wait for the hat trick delivery when rain arrived midway through the following over.