At this time of his career, his body is in the sort of state when he seems vulnerable a lot of the time. We can't get away from that but he's a hell of a player and we want him in our side if he's fit,' he said.
If Flintoff is unfit, fast bowler Steve Harmison will replace him. Flower said he was happy with Harmison's performance in the domestic season.
'I never drew any line under Steve. He's a very good fast bowler with a very good record for England, so he was always in our minds.
'He's in form, as is Graham Onions, but we'll look at the pitch and decide what balance of bowlers we want. He's a like-for-like replacement for Flintoff, but we'll see what is needed for the match,' Flower said.