New Zealand paceman Mitchell McClenaghan will join up with Worcestershire at the start of the second week in July.
McClenaghan will have a period of acclimatisation with the county before taking over from Saeed Ajmal as the county's overseas player.
He was part of New Zealand's squad for the ICC World Twenty20 in Bangladesh and had a successful period with Lancashire last season.
Ajmal is due to end his current spell with Worcestershire on July 17 after playing in the LV = County Championship match with Leicestershire at New Road.
Worcestershire Director of Cricket Steve Rhodes confirmed that McClenaghan is also on stand-by to complete the season should Ajmal be unable to return for the end of the campaign after Pakistan's August tour of Sri Lanka.
Rhodes said: "Around about July 7 is when Mitchell McClenaghan arrives so he will have a bit of acclimatising which is perfect and hopefuly hit the ground running when Saeed departs.
"Is there a chance Ajmal can come back? In many ways, that is exactly what we would like. We are ongoing with our communications with the Pakistan Cricket Board and we've just got to wait and see on that one.
"The good news for us is that Mitchell is also desperately looking forward to playing for us and he really wants to do well and he is also very flexible regarding the amount of time he can play.
"He is on stand-by to carry on for us if we can't get Saeed to come back after the tour of Sri Lanka. We are in the luxurious position of having all bases covered."
McClenaghan, who was 28 last week, took 11 wickets for his country in just three matches during last summer's ICC Trophy in England – including three against the host nation.