Worcestershire have lost Australian Callum Ferguson for this season's final three County Championship games.
New Zealand's Hamish Rutherford, 30, is to return as Ferguson is going back home to Australia for personal reasons.
The Pears have also said that injured pace bowler Josh Tongue will miss the final three games with a side strain.
Tongue suffered his latest injury during the Pears' 10-wicket defeat inside three days by Northants at Wantage Road.
Rutherford can also deputise for Ferguson as their second overseas player in the T20 Blast.
T20 holders Worcestershire are second in the group before Sunday's home game with leaders Lancashire.
They are ninth in Division Two of the Championship, 39 points off a top-three place with three games left.
Rutherford made 123 in his one Championship knock on his Pears debut in the innings win over Leicestershire in April - and also hit tons in two of his five One-Day Cup appearances.
Ferguson, like all of the Pears' top order, has struggled for runs this summer. He has compiled 503 in 10 Championship matches at 31.44, and hit 129 in eight T20 games.
Tongue took 12 wickets as Worcestershire won their first two Championship matches, but injuries had restricted him to just one appearance since, until he broke down at the end of the first day after his recall for the game with Northants.