England have underlined concerns about Andrew Flintoff's fitness by summoning two players to the Caribbean to cover for their injured all-rounder.

Essex batsman Ravi Bopara and Kent fast bowler Amjad Khan have left the second team Lions' tour of New Zealand and will join Andrew Strauss's squad in Barbados this weekend as doubts grow about Flintoff's availability for Thursday's Fourth Test against West Indies.

Flintoff will have a scan on his right hip tomorrow amid fears the injury-plagued cricketer faces another long-term problem in the run-up to this summer's Ashes.

Rain in Antigua this morning held up England's bid for victory on the final day of the Third Test with play delayed by 75 minutes. And, with the visitors needing seven more wickets to level the series after reducing West Indies to 143 for three by last night, the hold-up brought Strauss's tactics earlier in the match back into focus.

The new captain decided against enforcing the follow-on when West Indies were 281 behind and then stretched the lead to 502 before declaring yesterday.

Ramnaresh Sarwan and Shivnarine Chanderpaul, mainstays of the West Indies middle order, frustrated England last night and nudged the total to 164 for three this afternoon despite testing bursts from Steve Harmison and Jimmy Anderson.

Flintoff, fielding in the slips, was officially available to bowl “if needed” but he looked far from fit yesterday, despite having an anti-inflammatory injection in his hip on Tuesday.

He batted at No 9 and then, given just three overs after belatedly entering the attack, he was well below top pace and appeared unable to move anything like freely.

“The medical guys think there might be a little tear, they're not sure, but it is a muscle problem,” said assistant coach Andy Flower. “Andrew works really hard at his fitness but I think through workload and wear and tear over the year he keeps picking up these little injuries. He is a strong bloke, physically and mentally, and will get himself right, hopefully.”

After a career-threatening ankle problem, which required four operations, any injury suffered by the talismanic Flintoff sparks concern. And, at 31, his body seems to be protesting against all the bowling work it has been put through, with a side strain having almost forced the Lancastrian to miss the First Test of this series.

“We just hope he will be fit for the next Test in Barbados,” said Flintoff's fellow fast bowler, Harmison. “The big lad's in a bit of pain and it shows you the character he has that he even attempted to go out on the field and give it his all yesterday.

“He's got to take a lot of credit for that. There is a good medical team with us and if they thought he was doing serious damage they would have hauled him off.

“It would be nice to win this for him because, although he has not carried our bowling line-up, he has been our man to go to.”

Flintoff rarely gets the wickets his sterling work deserves. But he often softens up the opposition so that others can benefit and, without their main man's aggression yesterday, England struggled hard for successes on a pitch that has stayed stubbornly flat despite all the theories it would turn into a minefield for batsmen.

“I can't believe how well this pitch has played,” said Harmison, who struck the first blow of the second innings by removing Devon Smith after West Indies had reached 59 without loss. “It is flat but there's a demon in there. The bowlers can look silly at times because they're ploughing away on an area and it looks simple for the batters. But if you stay patient, now and again the ball does something.”

Harmison was himself struggling during West Indies' first innings, laid low by a stomach bug. “I was at death's door on Tuesday,” said the Durham paceman. “The first time I went off I was sick and after that the heat got to me.”

After Harmison removed Smith, spinner Graeme Swann accounted for one of West Indies' big three batsmen when captain Chris Gayle missed an attempted sweep to fall lbw. Then Ryan Hinds obligingly drove Stuart Broad straight to mid-on.