The 25-year-old brought his four-season spell at Gresty Road to an end when he agreed terms with manager John Ward's side and is excited by the challenge.

BBC: Carlisle move is right - Williams

U's boss John Ward is struggling for defensive options, with Magnus Okuonghae out with an ankle injury and Pat Baldwin suspended.

BBC: Huddersfield's Nathan Clarke makes Colchester switch

Tierney's contract was due to expire in the summer and U's boss John Ward admitted he was unable to persuade the left-back to sign a new deal.

BBC: Norwich City snap up Colchester defender Marc Tierney