Ashton Agar's record-breaking debut and Marais Erasmus' controversial third-umpire decisions combined to make day two of the 2013 Ashes every bit as dramatic as the first.

Australia's teenage number 11 transformed their fortunes at Trent Bridge, benefiting from the first of Erasmus' interventions when he was ruled not out stumped - on just six of the 98 he went on to make in a total of 280 all out.

Agar and Phil Hughes' all-time Test highest last-wicket stand of 163 rescued Australia from an apparently certain and significant first-innings deficit and instead put them 65 in front.

Erasmus' day was far from done, though, as he was to be pressed centre stage again when he overturned Aleem Dar's not-out decision - despite the unavailability of side-on 'Hotspot' evidence - as Mitchell Starc dismissed Jonathan Trott lbw for a golden duck.

That setback left England 11 for two at tea, before Alastair Cook and Kevin Pietersen at last restored order in a wicketless final session to close on 80 without further loss.

Day one of this much-hyped Investec series brought 14 wickets, under unshifting grey skies.

The clouds were absent today, but there was no let-up in the action - with a dash of controversy thrown in, as England sought clarification from match referee Ranjan Madugalle over the DRS procedure by which Erasmus gave Trott out.

Agar had earlier fallen agonisingly short of becoming the first Test number 11 to make a hundred, in company with Hughes (81no).

The 19-year-old was watched in the Nottingham crowd by his parents, who followed him round the world and were rewarded not only by a surprise debut but a remarkable innings.

Agar took guard after James Anderson (five for 85) had this morning kickstarted a rush of five wickets for nine runs as Australia lurched to 117 for nine.

He played barely a false or mistimed shot until Stuart Broad had him caught pulling to deep midwicket, to end a 101-ball innings which contained 12 fours and two sixes.

Shell-shocked England appeared to run out of ideas, holding back Broad - passed fit to bowl at start of play, despite the shoulder injury he suffered last night - for almost two-and-a-half hours as Agar and Hughes extended the morning session by 30 minutes.

First-class playing conditions dictate that curiosity, once a team has nine wickets down, and England fell foul of the rule for the second time in as many years.

It was only last summer they last ran into a number 11 in world record-breaking form, when West Indies' Tino Best smashed 95 at Edgbaston.

This time, Agar's astounding performance was almost nipped in the bud when England thought they had him stumped off Graeme Swann with the total on 131.

Erasmus made a marginal call otherwise, though - and Australia's teenage sensation never looked back.

Agar's innings was full of pedigree shots, and clean striking, which belied his position and will surely mean he makes a career for himself much higher up the order.

In Broad's absence, Steven Finn's bowling was erratic after Steve Smith (53) had hit the first half-century of the series only for an apparently terminal collapse to take hold around Hughes.

Anderson demonstrated yet again this is one of his favourite hunting grounds, starting when Smith went for one drive too many and edged behind.

Brad Haddin was bowled on the back foot by a Swann off-break, and Anderson upped the ante with his second wicket in successive overs.

Peter Siddle edged an attempted drive low to diving wicketkeeper Matt Prior to depart, like Haddin, for just a single.

Starc could not even get off the mark, already dropped at second slip by Swann off Anderson before he instead became the England pace spearhead's third caught-behind victim.

Swann made it nine down when James Pattinson was lbw despite a DRS review.

But Hughes and Agar were in no mood to go quietly - not before they had chalked up several notable pieces of cricket history and altered the complexion of this manic contest, anyway.

England's second innings hinted only briefly at calm before Starc put himself on a hat-trick for the second time in the match, Joe Root caught down the leg-side and then Trott bang in front to an inswinger.

Dar presumably detected a faint inside-edge, as did many others on video replay, but the absence of 'Hotspot' corroboration was enough for Erasmus to overrule.

If England felt wronged, they responded impressively as Cook and Pietersen - both escaping half-chances to wicketkeeper Haddin off Agar, on 25 and 30 - shared an unbroken stand of 69 to sneak 15 runs in front.