But Joe Root once again was England's saviour, with a majestic knock of 134 that put Cook's men in charge at the end of an enthralling day. England finished on 343/7 - only slightly on top.
Australia made best use of the inclement morning weather, taking three early English wickets. After the start was delayed, Cook and Adam Lyth walked out to bat amid great fanfare. Urged on by a packed SSE SWALEC crowd and played onto the pitch by the vocal talents of Only Men Aloud perhaps the inexperienced Lyth was overawed by the occasion. He was soon dismissed for 6, edging to third slip David Warner off the bowling of Josh Hazelwood.
Cook soon followed, nicking to Brad Haddin off Nathan Lyon and Ian Bell continued his struggles with the bat, trapped LBW by Mitchell Starc.
The great rebuilding job done by Root and Gary Ballance put England firmly in the driving seat. The Yorkshire duo went the entire afternoon session without losing a wicket and rarely looked troubled on a pitch that appeared fairly play. And even after losing Ballance for 61, Ben Stokes came in and gave the innings great impetus, moving England's score onto 280/5.
But Australia are a resilient outfit these days, not like their 2013 squad, which may have wilted after such a tame afternoon's display. Root and Stokes fell in quick succession, both to the dangerous (but expensive) Starc, who took 3/84. Stokes was undone by a beauty from the Australian left-armer, departing for a well-made 52. The biggest cheer of the day went to Root who acknowledged the crowd who gave him a hearty Welsh send-off for a fantastic hundred.
When Moeen Ali and Jos Buttler came together, it looked like England would claim a healthy advantage at the close of play. Buttler then fell tamely, caught at mid-on by Mitchell Johnson off the impressive Hazlewood. The young seamer finished with figures of 3/70 on his Ashes debut. Ali and Stuart Broad saw out the bowling, the Worcestershire batsman closing 26*.
An action-packed start to the Ashes summer then and tomorrow looks set to be another thrilling day, as England seek to cement a strong position.
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