Nathan Lyon flies into England on Monday to begin his month long spell with Worcestershire.
The leading Australian off spinner will replace his compatriot, John Hastings who will be in ICC Trophy action.
Hastings has made a big impression already at New Road but Worcestershire have signed another quality overseas player in Lyon who has taken 247 wickets in 67 Tests.
Director Of Cricket Steve Rhodes said: "John has done a great job with the parts he has played and also been brilliant in a leadership capacity for the group.
"He has got that winning mentality and he drives the boys on. Not to have him will be a blow – but we have signed a quality replacement in Nathan Lyon.
"He will get here early on Monday morning and we look forward to him joining up with us."
Lyon, who is set for a key role against England in the Ashes at the end of the year Down Under, is looking forward to a return to action and a first stint of county cricket.
The 29-year-old last played at the end of March in the India-Australia Test series during which he returned a career best 8-50 in Bengaluru.
Lyon said:"I've had about five weeks off and I've got the itch to get out there bowling again.
"I'm looking forward to getting back to compete, and adapting to different conditions. They'll be different wickets to what I'm used to and they'll be challenging.
"I'm still trying to learn things about my game as well on and off the field."