Joe Root remained unbeaten on 178, as England went into stumps on Day 3 in a commanding position at 333 for 5, with a mammoth 566-run lead.
London: Opening batsman Joe Root hit an undefeated 178 against Australia as England took a huge 566-run lead after closing the third day on 333 for 5 in the second Test at Lord's on Saturday.
Captain Alastair Cook opted against a declaration and a few overs of bowling in the evening session in a Test England are well placed to win for a 2-0 lead in the five-match series.
Australia, which were bowled out for only 128 in their first innings, will need a record fourth innings Test total to win with two days left in the match. West Indies' 344 for 1 in 1984 is the only occasion a team has scored more than 300 to win a Lord's Test.
Jonny Bairstow on 11 was with Root at stumps, after Ian Bell scored 74 and nightwatchman Tim Bresnan made 38.
Seeking a third straight Ashes series victory, England dominated the match all day though Australia endured another umpiring controversy.
Bell edged fast bowler Ryan Harris low down to Steve Smith at gully when on 3, but waited to check with the umpires whether the ball had carried. Third umpire Tony Hill ruled in Bell's favour much to the Australians' annoyance. In the first Test at Trent Bridge, Stuart Broad declined to walk despite clearly edging to slip with Australia out of referrals.
Bell went on to score 74 and shared a partnership of 153 with Root and took the game away from the tourists.
Australia promised so much after its attempt to win the first Test failed by just 14 runs. But it has failed to back up that display this time round.
England, which made 361 in the first innings, will likely declare overnight or early on day four and look to dismiss Australia a second time.
The pressure was on the 22-year-old Root entering this series, despite his century against New Zealand earlier in the summer. Nick Compton was omitted as Alastair Cook's opening partner for the Ashes and Root was promoted, meaning he had to prove himself all over again. He did so at Lord's.
Root patiently applied himself with a 334-ball stay at the crease, putting on 99 with Bresnan.
Root's run rate was slow at times, as Australia bowled accurately after lunch, but after tea he cut loose to advance from 97 to 178.
At one point Root and Bell managed 71 runs in 10 overs.
Root, whose only error was an edge inbetween wicketkeeper and slip when on 8 on Friday, cut teenage spinner Ashton Agar for his 12th four to go to three figures.
The Yorkshireman also became the first to 1,000 first-class runs in the English summer, when he reached 70. He has six centuries this summer.
Root's two sixes off leg-spinner Smith within three balls in the penultimate over of the day demonstrated his growing confidence.
Bell earlier got himself out when looking like he was racing to his third consecutive century this series, when he pulled a long-hop from Smith to midwicket.
Not much went right for Australia all day, though. Even tailender Bresnan survived the entire morning session before he hooked James Pattinson to midwicket.