Michael Powell: could make his England debut at Old Trafford © Getty Images Enlarge

England have called up Surrey's Rikki Clarke and Michael Powell of Glamorgan to their NatWest Series squad as cover for the injured Marcus Trescothick and Andrew Flintoff.

Flintoff is only rated as "50-50" to play in the opening game against New Zealand on Thursday after suffering an injury to his left foot during the third-Test victory at Trent Bridge. Trescothick, meanwhile, twisted his left ankle during fielding practice at Cardiff before England's warm-up match against Wales last week. Even though an X-ray showed there was no break, he will continue to receive treatment over the next 48 hours.

Clarke, 22, has played 16 one-dayers for England, and was in both the Test and one-day squads to tour Bangladesh, Sri Lanka, and the West Indies last winter. An allrounder, Clarke averages just under 10 with the bat, and has taken 10 wickets.

Powell, 26, made his first-class debut for Glamorgan in 1997, and has been a consistent performer in the top order, averaging a little under 40. He nearly made the original squad, but missed out at the last minute. He played against England for Wales in the warm-up match at Cardiff last week, scoring 49 as Wales lost by six wickets.

While Powell and Clarke will have to wait to see whether they will line up against New Zealand, one player who is likely to benefit from Trescothick's absence is Robert Key. He made his mark with 83 from 95 balls against Wales in Cardiff on Saturday, and has expressed a desire to remain as an opener.