Director of Cricket Steve Rhodes said Worcestershire would consider all options for their 2018 overseas player slot after John Hastings announced his retirement from first class and one-day cricket.
Hastings had been due to return to New Road for a second campaign next summer as their main overseas player.
But he will now ply his trade solely in T20 cricket after a succession of injuries had taken their toll on the Australian all-rounder with a back injury the final straw.
Hastings, 31, is still keen to return to New Road for the NatWest T20 Blast.
But he fully understands that Rhodes and Worcestershire have to consider all possibilities when weighing up who will fill their overseas berths.
Rhodes confirmed: “John has retired from first class and one-day cricket because of injury. We are very disappointed for him.
“He is a top bloke and made a big impression on our dressing room. I know people like Josh Tongue have praised the part he has played in their development.
“He was signed up with us for two years, I have spoken to him today and he was desperate to come back next summer.
“But he will now be concentrating on purely playing 20 over cricket.
“John is going to be playing in the Big Bash for Melbourne Stars and he has said he wants to come and play in the T20 Blast for Worcestershire.
“But John understands we have to consider all our options in terms of our overseas players for 2018.”
Hastings told cricket.com.au: “Trying to get back after four shoulder reconstructions, four major ankle operations and a major knee operation has just worn me down.
“The body is just giving up and every time I try to load back to get back to four-day cricket or one-day cricket, it seems as if something else goes.
“It was a tough decision, one that wasn’t made lightly, but I’ve decided to give the two longer formats away and focus on T20. I’ve still got a bit left in the tank though.”
The right-armer played 29 ODIs and nine T20 internationals in the green and gold and had his best year in the 50-over game last year.
In 2016 Hastings was the world’s leading ODI fast bowler after snaring 29 wickets in 15 matches, the equal second-most dismissals alongside South Africa’s Imran Tahir and behind teammate Adam Zampa.
Cricket Australia chief executive James Sutherland descibred Hastings as a “brilliant” competitor.
He said: “John has been a great servant of Australian cricket, and a player who worked extremely hard to be the best he could be, both at national and domestic level, and we congratulate him on his achievements.
“While it is unfortunate that we will see less of John in action, we wish him the best of luck in his role as captain of the Melbourne Stars for this summer’s KFC Big Bash League and the future ahead.”