LEEDS: England's selectors added left-arm quick Ryan Sidebottom and uncapped batsman Jonathan Trott to the 14-man squad they announced Tuesday for the fourth Test against Australia here at Headingley.

All the 11 players, including Andrew Flintoff, who took the field for the drawn third Ashes at Edgbaston retained their places.

Meanwhile in form fast bowler Stephen Harmison, who was in the squad for that match but didn't play, also kept his place despite bowling with blistered feet for county champions Durham.

England have tried to plan for fast bowling all-rounder Flintoff's possible absence through a longstanding right knee injury by giving themselves additional pace bowling options in Harmison and Sidebottom, who has been taking wickets for Nottinghamshire, as well as an extra batsman in Trott.

England are 1-0 up in the Ashes with two Tests to play.

If Trott does make his debut at Headingley, his inclusion could see England playing six batsmen as they bid for a victory that would see them regain the Ashes after they were thrashed 5-0 in Australia in 2006/07.

"We will need to carefully assess the pitch and the overhead conditions at Headingley before finalising our eleven for this Test and the inclusion of Stephen Harmison and Ryan Sidebottom will give us different types of pace bowling options," said England national selector Geoff Miller.

"Both players have been in good form for their counties in recent weeks and as selectors we are delighted that competition for places in the side is so strong."

There are just three days between the end of Monday's match at Edgbaston and Friday's start at Headingley.

Flintoff top scored with 74 at Edgbaston but looked at times to be struggling with his knee injury.

Having bowled England to victory in the second Test at Lord's, he went wicketless at Edgbaston and in both matches he needed injections before he could take the field in what Flintoff has said will be his final Test series.

"We will continue to closely monitor Andrew Flintoff's fitness in the build-up-up to Headingley," said former England off-spinner Miller.

"His right knee will be reassessed by our medical staff over the next forty-eight hours and no final decision on his availability will be taken until closer to the start of the Test match."

Sidebottom - included in a Test squad for the first time this season - knows Headingley well, having started his career there with Yorkshire while Harmison, although erratic at international level, remains England's quickest bowler.

Former England captain Nasser Hussain has been among those questioning the current side's ability to take 20 wickets in a Test if the ball is not swinging and Harmison's raw speed would give the attack a different dimension.

At Edgbaston, England didn't have a spare batsman after 28-year-old Trott's Warwickshire colleague Ian Bell was recalled after Kevin Pietersen's series-ending Achilles injury.

Trott, like Pietersen born in South Africa, found his only previous experience of international cricket tough going, scoring 11 runs in two Twenty20 internationals against the West Indies at the Oval three years ago, but he has impressed at county level.

"Jonathan Trott has also performed really well for Warwickshire this season and his place in the squad is fully deserved," Miller said.

"His inclusion will provide us with the option of playing six batsmen if we feel this is appropriate.

Left-arm spinner Monty Panesar, in the squad at Edgbaston but not selected for the match, was left out on Tuesday.

"We decided to omit a second spinner as Headingley is not usually a ground where two spinners are required and therefore Monty Panesar misses out on selection this time," Miller explained.

England squad:

Andrew Strauss (capt), Alastair Cook, Ravi Bopara, Ian Bell, Paul Collingwood, Matthew Prior (wkt), Andrew Flintoff, Stuart Broad, Graeme Swann, James Anderson, Graham Onions, Stephen Harmison, Ryan Sidebottom, Jonathan Trott