Mash Off
Special guest star Idina Menzel is featured as rival glee club director Shelby Corcoran , and she and Will Schuester ( Matthew Morrison ) hold a mash-up competition between the Troubletones and the New Directions . 
<triplet> Shelby Corcoran <subj> Idina Menzel <obj> performer <triplet> Will Schuester <subj> Matthew Morrison <obj> performer