[{"objectList":[{"toChange":0.0,"toMatch":"bar"}],"array":["first","second"]},{"objectList":[{"toChange":0.0,"toMatch":"bar"}],"array":["second","first"]}]

db.collection.update({array:{$in:["second"]}},{$set:{"objectList.$[x].toChange":10}},{arrayFilters:[{"x.toMatch":{$exists:true}}],multi:true})