England require six wickets on the final day in Adelaide to win the Second Test after Kevin Pietersen rocked Australia's hopes of survival with the wicket of Michael Clarke in the last over of day four.

A rain interruption and a fighting stand appeared to have given the home side a boost, but Pietersen's gentle off-spin proved the measure of the impressive Clarke, ending a 104-run partnership to give England's victory hopes a massive shot in the arm going into Tuesday's fifth day.

At the close the Australian total was 238 for four, still trailing England by 137 runs after the visitors had declared with a first innings lead of 375.

Earlier Andrew Strauss forfeited the opportunity of bowling first up and opted instead for the safety of more runs. While the England captain's decision was conservative, Kevin Pietersen, Ian Bell and then Matt Prior were anything but as they held nothing back in the opening nine overs of the day.

Pietersen quickly moved to a new personal best Test score of 227 before he fell playing an agriculture hoick off, ironically, the left-arm spin of Xavier Doherty. Matt Prior then took over the offensive, finding his first runs in the series, surviving a lbw decision on review and then smashing a quick-fire 27 as he and Bell added 52 runs in just 34 balls.

In another spotless half-century, Bell (68 not out) played aggressively with the elegance which suggested that given more time at the crease he would surely have collected a first Ashes ton. Having added 69 runs to their overnight score, England declared on a mammoth 620 for five.

In response the Australian openers started positively. Katich, hobbling between the stumps due to an achilles injury, and Watson, in characteristically stubborn mood, saw off the new ball with Jimmy Anderson unable to reproduce his first innings form.

The arrival of Graeme Swann into the attack came as early as the 10th over but his captain was once again guilty of being overly defensive with three men on the fence and not enough fielders catching for the start of the off-spinner's spell.

Slowly Swann found his range and only good fortune saw the Aussie openers safely through to lunch with a number of bat-pad chances landing in open space. The only catch that did go within range of a fielder was a half-chance from Katich, the left-hander flicking the ball through the legs of Alastair Cook at short leg.

Katich and Watson had laid the platform for Australia's survival bid but it was to be rocked by the increasingly threatening and confident Swann. With none of England's seamers able to make any impact, England's prize off-spinner proved invaluable as he struck twice, removing Katich (43) and then claiming the massive wicket of Ricky Ponting (9) shortly afterwards.

At the other end Watson bagged another half-century and then repeated his frustrating habit of getting out in the 50s when he was undone by Steve Finn. It was a great delivery from the tall Middlesex man who put in a fine afternoon spell which included a hint of reverse-swing - England's bowlers showing far more edge than their Australian counterparts.

With the home side in trouble on 134 for three, Michaels Hussey and Clarke set about rebuilding the innings and were aided by a rain interruption mid-way through the last session.

Clarke, who survived a scare on 67 when the umpire review kept him at the crease, played with the freedom which his batting has missed in the recent past and led the Aussie fight with solid support from the in-form Hussey (44 not out). The pair added 104 before Kevin Pietersen's off-spin claimed Clarke for 80 in the final over of the day.

With just Marcus North and Brad Haddin to come before the lengthy Aussie tail, the forecast of rain in Adelaide on Tuesday appears to be Australia's greatest chance of stealing a draw.

Shot of the Day
Shane Watson put together another attractive half-century and went to the milestone with a particularly elegant on-drive for four. His penchant for driving cost him his wicket in both innings in Adelaide but it is a stroke which brings him plenty of runs and is a joy to watch.

Delivery of the Day
Steve Finn proved his worth with a telling delivery that was too good for key man Watson, who lent forward to edge through to Andrew Strauss at first slip. It was the perfect length delivery to draw the Australian opener forward and seamed just enough to kiss the outside edge. Graeme Swann's ripper past the outside edge of Hussey's bat also deserves a mention with the off-spinner set for a major role on on Tuesday.

Defining Moment of the Day
The wicket of Michael Clarke in the final over of the day was a massive blow to Australia's hopes of survival, with the body language of the Aussie dressing room a dead giveaway as to their mood.

Doug Saxby