He will stand-in for Jim Troughton, who has been appointed assistant coach for Birmingham Phoenix in The Hundred.

Westwood will be assisted by bowling coach Graeme Welch for the eight group games of the 50-over competition.

"I've been very impressed with Ian and he has the makings of an excellent coach," said the club's Sport Director Paul Farbrace.

Westwood helped Warwickshire to two County Championship title wins before retiring in 2017 and joining the club's coaching staff.

He became head coach of the second team last year.

The One-Day Cup and The Hundred are both being staged at similar times during July and August.

Worcestershire announced a similar arrangement in February with assistant coach Alan Richardson set to take on One-Day Cup duties while head coach Alex Gidman works with Birmingham Phoenix.