Saeed Ajmal, the Pakistani mystery spinner, returns to begin his third spell for Worcestershire on Friday night against Northamptonshire but, having remodelled his action, faces the challenge of regaining his potency.

Worcestershire had Ajmal at his best last season, helping them to both promotion in the County Championship and to a NatWest T20 Blast quarter-final, but over the winter his action was found to be illegal by the ICC and he has undergone remedial work.

Since returning for Pakistan, Ajmal has struggled, taking 1 for 123 in two ODIs against Bangladesh in April, conceding 6.47 an over, over two runs more expensive than his career economy rate. A cloud now hangs over his future, and Worcestershire will be hoping he can return to the form of 2014.

Bazid Khan, the former Pakistan batsman, has questioned whether Ajmal could ever be the same bowler again. "The fact is that Saeed Ajmal was getting prodigious amount of spin and his doosra was effective due to the flex in his previous action," Khan told "I don't think he will ever be the same bowler again.

"Whilst we know he is hard working and big-hearted, unless he can reinvent himself as a bowler who can stop runs in the mid-overs and keep it tight, he will struggle to keep his place in the Pakistan team. We can give him a year or so to prove himself but in my view, his potency with which he used to bowl at his opponents will never be the same again."

Worcestershire, heavily reliant on Ajmal, such pessimistic expectations of his decline will prove unfounded.

Ajmal also worked closely with Moeen Ali, who was picked as England's specialist spinner last summer. Moeen also returns for Worcestershire on Friday having been left out of England's one-day squad to concentrate on his spin bowling with the red ball. Moeen also has a part to play in the NatWest Blast but his focus will be on the three County Championship before the start of the Ashes on July 8.