SYDNEY, Jan 5 (Reuters) - David Warner and Marcus Harris ushered Australia to an early lunch at 30 without loss after a rain-disrupted first session of the fourth Ashes test against England at the Sydney Cricket Ground (SCG) on Wednesday. The toss was delayed by 30 minutes after heavy early morning showers and there were still dark clouds over Sydney"s eastern suburbs when Australia skipper Cummins elected to send his openers in. They weathered fewer than five overs of seam bowling from England"s Stuart Broad and James Anderson before the skies opened again. The openers returned after a lengthy break but the covers were soon on again when another shower swept in from the Pacific Ocean. Only 12 1/2 overs were possible before lunch. Warner will resume for the second session on 15 not out, while Harris was unbeaten on 11. Australia have an unassailable 3-0 lead in the five-match series after big wins in Brisbane, Adelaide and Melbourne, leaving the tourists playing only for pride as they seek a first test win Down Under in 11 years. The hosts brought Usman Khawaja into the middle order in place of Travis Head, who tested positive for COVID-19. With Ollie Robinson and Chris Woakes both struggling with shoulder problems, England recalled Broad after the veteran bowler missed two of the first three tests. The fifth test, originally scheduled for Perth, will take place as a day-night match in Hobart from Jan. 14-18.