Paul Collingwood's injury niggles have left England's selectors with an anxious wait ahead of the first npower Test squad announcement on Sunday morning.

Collingwood is suffering from a lower back problem less than a week before the Lord's contest against New Zealand and was due to have an injection in an ongoing right shoulder injury this evening.

Wicketkeeper Tim Ambrose is also troubled with a stiff neck and received treatment rather than take the field for Warwickshire today.

But England one-day captain Collingwood will provide a headache for a new-look panel headed by Geoff Miller.

"Paul has received treatment for stiffness in his lower back and a sore right shoulder," said an England and Wales Cricket Board spokesperson. "He will continue to receive treatment and be reassessed over the next 48 hours."

Collingwood, 31, would be an integral part of any plans to field Andrew Flintoff in a four-man attack in the series opener.

Although Flintoff is deemed fully fit following a fourth ankle operation, England would not want to bowl him into the ground and Collingwood could supplement the attack with half-a-dozen to 10 overs a day.

England are likely to select all-rounder Flintoff for his form with the ball as he bids to play his first Test since the final 2006-07 Ashes defeat.

Flintoff has looked smooth from the off in his latest comeback and his early-season menace was rewarded with seven wickets in the defeat of Collingwood's Durham at Old Trafford.

The 30-year-old has mustered only 68 runs in seven innings for Lancashire this summer, however, twice falling for nought in his latest outing.

That is not the kind of form to merit a place in the top six and he is being lined up to slot back in at number seven, a position in which he has not been selected since the tour of Sri Lanka in 2003-04.

England's established batsmen have hardly been rich in runs themselves, however, with captain Michael Vaughan's lack of a half-century this season of concern and Collingwood in a real rut.

He has scored just 32 in five innings in all forms of cricket so far, leaving him somewhat undercooked.

Nevertheless, Collingwood's most redeeming quality as an international batsman is an ability to tough things out in difficult times and he said: "It's a bonus if you can come out and score hundred after hundred every innings.

"Realistically it's not going to work that way and you come up against difficult conditions.

"Runs would be good to get that confidence going but I'll back myself to go out there and score out in the middle when the time comes.

"I am sure that everybody has got me down as the first one off the team sheet but I am a battler.

"It is disappointing not to score runs but the big ones could be just around the corner."

Collingwood's last hundred in England whites came 10 Tests ago while Vaughan is also under pressure for a score after an off-colour series in victory in New Zealand.

Two runs in as many innings against the students of Bradford and Leeds preceded 95 in three County Championship efforts - each time starting well before falling when set.

But he does have a good personal record at Lord's, the scene of five of his 17 Test hundreds.

The rest of the top order have fared little better in the opening weeks, however, with only Kevin Pietersen convincing that rest has been beneficial with a comeback 100 against Somerset this week.

Ian Bell has scored runs regularly but not developed that into a three-figure score, Alastair Cook had one hundred prior to Essex's match against Middlesex, for whom Andrew Strauss hit a well-timed 88.

Strauss, who secured at least one more series at Test level with a career-best 177 in his sixth and final visit to the crease against the Black Caps in March, began the season with 163 off a patched-up Surrey attack in a one-day encounter.

Another recent centurion, Ambrose, sat out Derbyshire's second innings at Derby today as a precautionary measure given the proximity to the first Test of three inside a month, and received massage treatment.

Given Collingwood's fitness, national selector Miller's first home squad could include an extra body as standby batsman with Owais Shah, Robert Key and Ravi Bopara at the head of the queue.

If Flintoff is to return as part of a four-man attack - and all the noise from captain Vaughan and coach Peter Moores suggests he will return at the earliest opportunity - then there will be at least one change from the XI which secured a 2-1 comeback victory against the Kiwis.

Flintoff's Lancashire colleague James Anderson appears the most vulnerable of the pacemen - despite nine for 77 against Durham - with Ryan Sidebottom now indisputably first choice with the new ball and Stuart Broad's youthful vigour demanding selection.

With competition for places intensifying, Matthew Hoggard made the most of the helpful conditions at Headingley to take eight Hampshire wickets last month but may have to wait for an opportunity to add to his 248 Test victims.

Possible squad: Vaughan (captain), Strauss, Cook, Pietersen, Bell, Collingwood, Bopara, Flintoff, Ambrose (wicketkeeper), Broad, Sidebottom, Panesar, Anderson.