Fast bowler Tymal Mills will miss the start of Sussex’s Twenty20 campaign after suffering a recurrence of a mysterious back problem.

The Sharks launch their NatWest T20 Blast campaign at Kent tonight before welcoming Gloucestershire to Hove on Sunday.

Mills was expected to be a key player in the shortest format of the game for Sussex this season having signed from Essex during the winter.

But the 22-year-old broke down during the Championship game against Worcestershire four weeks ago after experiencing numbness in his lower back.

Coach Mark Robinson has confirmed it is the same problem which sidelined him for the second half of last season saying: “It is to do with his spinal cord so it is quite worrying as the long-term effects could be serious “The medical team and Tymal have to be very, very careful and at the moment they are not 100% sure what is causing the problem.

“It is a very unusual injury as nobody has seen it before in other sports let alone cricket. There are not many people who bowl at 90mph-plus like Tymal so there are not a lot of case studies to look at.

“At the moment he has been given the all clear to start bowling again but we’ve not got a timescale on any comeback yet and if he gets any recurrence of the symptoms then he will have to stop.”

Ajmal Shahzad is also expected to miss the trip to Kent tonight having torn a pectoral muscle during the Championship game against Middlesex on Sunday with Chris Jordan unavailable having been named in the England squad for the first Test against New Zealand yesterday.

Skipper Luke Wright said: “We’ll see where Ajmal is but it is disappointing to lose Millsy as the way he played in Dubai (during pre-season) showed how much of an asset he was going to be for us this season with his pace.

“We’ve seen in games all over the world that pace gets you wickets in the middle overs which is massively important but it does give someone else a chance to step up and stake a claim.”