Ryan Harris and Peter Siddle got Australia off to a flying start in their thrilling pursuit of a third Test victory on day five at Old Trafford.

However, with Australia needing to win the match to keep the Ashes alive, and wet weather threatening to spoil their party at any moment, it remains to be seen how crucial a Michael Clarke dropped catch off Joe Root will prove in the final wash-up.

At lunch on the final day England are 3-35 from 20 overs, with Harris taking 2-13 from seven and Siddle 1-6 from three.

Root is not out 13 and Ian Bell unbeaten on two, with England already out of DRS reviews.

Harris trapped England skipper Alastair Cook (0) plumb lbw in the third over of the day to leave England 1-0.

He had a excruciatingly close lbw review on Jonathan Trott turned down by umpire’s call, but got his man nicking down the leg-side (11) in the next over.

Siddle had Root edging to Clarke at second slip when brought on for his first over, but a simple chance was grassed, the ball hitting the skipper on his wrists.

However, the magnitude of the missed chance was tempered in Siddle’s next over when he had first innings centurion Kevin Pietersen controversially out edging behind.

Behind the wicket, keeper Brad Haddin and the slips cordon were convinced there was a nick, and umpire Tony Hill raised his finger.

Siddle had barely appealed and Pietersen immediately signalled for a review, adamant he hadn’t hit it.

HotSpot showed nothing, but there was a noise and the umpire’s decision stood.

Pietersen (8) was absolutely ropeable with the decision as he walked from the field, England at 3-27.

England players didn’t arrive at the ground until half an hour before play was originally scheduled to start, believing rain was going to save them from having to go out to bat.

But the Manchester skies cleared and play was underway just 30 minutes late at 11.30am local time, with 98 overs available for the day, weather permitting.

Australian skipper Clarke declared at 7(dec)-172 setting England a virtually unchaseable 332 for victory.

Australia maintained the pressure all morning, with Clarke even bringing himself on to bowl his first over of the series in the over immediately before lunch.

Left-armer Mitchell Starc (0-6) shared the new ball with Ryan Harris but bowled too wide in his opening spell, barely making the batsmen play from his four overs.