S4, E15: When Grace (Debra Messing) is invited to her ex-fiancé’s (guest star Tom Verica) wedding, she hauls along a reluctant Will (Eric McCormack) just to convey a false air of success - but when she denigrates the bridegroom's faults at the rehearsal dinner, she's confronted by a weeping bride-to-be (guest star Jennifer Aspen) who now wants to flee. Meanwhile, Elliot's (Michael Angarano) fuming mother (guest star Rosie O'Donnell) gets in Jack's (Sean Hayes) face when he allows Elliot to frost his hair and demands that he never see his son again. In addition, Will poses as a swinging tennis pro until he meets his match. Megan Mullally also stars.