England run-machine Ian Bell delivered another century from his Ashes series production line to engineer a spirited fightback on the third day of the fourth Test against Australia on Sunday.
Ryan Harris sent shudders through the home dressing room by grabbing three early wickets but Bell weathered the storm with a majestic unbeaten 105 that led England to 234 for five in their second innings at the close, an overall lead of 202 runs.
The low-scoring game is still tantalisingly poised with two days to go and, with the wicket getting lower and also offering increasing turn for the spinners, Australia will not want to chase more than 270 or 280 in the last innings.
Kevin Pietersen and Jonny Bairstow gave Bell solid support, contributing 44 and 28 respectively.
Root was the first man to go, clean bowled for two by a perfect delivery that pitched on middle before uprooting his off stump.
Captain Cook (22) followed his fellow-opener back to the pavilion with the total on 42, playing a poor shot to a wide ball and feathering a catch behind to Brad Haddin.
Harris claimed his third victim seven runs later when Trott (23) gloved a short ball down the leg side and Haddin swooped for an athletic catch.
Bell was then joined in the middle by Pietersen and the pair repelled Australia's assault with a stand of 106, a fourth-wicket alliance that could eventually prove a match-winner.
The tourists were hampered when all-rounder Shane Watson was unable to finish his seventh over because of pain around his right hip and groin.
Australia wasted an lbw review when Pietersen was hit way outside the off stump by Jackson Bird but they did not have to wait much longer to remove the South African-born batsman.
Pietersen tried to play off-spinner Nathan Lyon through the leg side and only succeeded in lofting a gentle catch off the leading edge to Chris Rogers at extra cover.
Bairstow carried on the good work, adding 66 for the fifth wicket with Bell who was in his element as he conjured a host of delicious cover drives and delicate late cuts.
The 23-year-old Bairstow, keen to avoid getting bogged down as he did in the first innings, was much more aggressive this time and hit two successive fours off both Lyon and Harris before being caught behind off the spinner.
Bell was knocked off his feet by a vicious bumper from Harris but the England batsman had the last laugh, bringing up his 20th test century just before the close with a single to mid-on off Bird.
He celebrated by punching the air before shaking the hand of nightwatchman Tim Bresnan who finished undefeated on four.
Earlier, Australia added 48 runs to their overnight 222 for five before being bowled out for 270.
Opener Chris Rogers fell for 110 while Stuart Broad finished with figures of five for 71.
Matt Prior produced a spectacular sprawling catch off spinner Graeme Swann to remove Rogers and the last wicket fell in comical fashion.
Umpire Tony Hill gave Harris not out following an lbw appeal from Broad but England decided to review the decision.
By the time it came for Hill to raise his finger, no one was left in the middle because the players had seen the television replays on the big screen in the corner of the ground and had already made up their minds that Harris was out.
England lead the five-match series 2-0.
Image: Ian Bell of England celebrates reaching his century
Photograph: Gareth Copley/Getty Images