Liverpool V Arsenal is now taking place before Arsenal V Liverpool so for the sake of simplicity I'd suggest game at Liverpool should now be regarded as first leg and game at Arsenal as second leg, so Oliver is still refereeing first leg but the first leg is now not at Arsenal but at Liverpool, so whoever was pencilled in for the second leg can still referee the second leg but this will no longer be at Liverpool but at Arsenal, where the first leg was originally meant to be.
Simplicity like i said...
Good appointment for Marriner. I did think Oliver was a likely choice for Man City V Chelsea but maybe not now he's refereeing on Thurs night and that game's on Sat lunchtime.
Will Probably be Taylor now
Could be Tierney/ Kavanagh, maybe even Attwell but I doubt that after his last performance