Is it usual for the AVAR to be an AR, as thought it was normally a ref, but Lee Betts is with Michael Oliver this week.
I was thinking that.
Perhaps it indicates the lack of English FIFA referees. If Attwell/Tierney are out on Wednesday or Thursday - eitehr as VARs in Champions League or refereeing in Europa League - then it might be they're struggling for numbers with Pawson away currently.