Instead of a glamorous tie with Wasps, the 25-year-old will turn out for Ayr as Glasgow have already made their one permitted change in squad personnel in the pool stages.
He will also miss next week's trip to Newport Gwent Dragons and a Glasgow statement admitted Beattie's quicker-than-expected recovery had taken them by surprise.
"We are delighted that Johnnie Beattie has recovered from the shoulder surgery he underwent last summer," said a Glasgow Warriors spokesman.
"As our medical team state frequently, recovery from serious injury is not an exact science.
"Johnnie is focusing on performing for Ayr in the British & Irish Cup against Birmingham & Solihull on Sunday - a match that will be watched by a member of the Scotland coaching team - and we wish him and Ayr all the best in that fixture."
Having sat out of the autumn internationals Beattie was looking to step up his recovery with two European outings for the Warriors who travel to Newport Gwent Dragons on 23 January after this weekend's tie.