India off-spinner Ravichandran Ashwin will be unable to play for Worcestershire in the closing weeks of the season as he is struggling with a groin injury.
The 31-year-old enjoyed a successful stint at New Road last summer and the Pears had been hoping that his return would be a major boost as they battle to avoid relegation from County Championship Division One.
However, having missed the final match of the ongoing Test series with England, Ashwin is still some way short of the level needed to fulfil his county commitments.
CEO Matt Rawnsley told the official Worcs CCC website: "It's a shame Ravichandran Ashwin will not be able to return to us because he made such a big impact here in 2017 and was keen to come back.
"He has gone on record about how much he enjoyed it here last summer, but the injury he has been struggling with in the Test series against England means that it is not possible and we wish him all the best and a speedy recovery."
Meanwhile, the opportunity to bring New Zealand batsman Martin Guptill back to the club for T20 Blast Finals Day has also been lost with the powerful right-hander struggling with a hamstring injury.
Rawnsley added: "The news is not good regarding Martin Guptill either. We had been in touch about whether there was a chance of him coming back for Finals Day.
"Sadly he is laid low with a hamstring injury and will not be able to return."
Worcestershire are 3/1 to win the T20 Blast title, with Somerset 11/4 and Lancashire 5/2.
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