This happened to me once in a match that my opponent offline and I am there with one supporter. I was leading 1-0 around 20 minutes and the opponent's GK injured before end of half time but no one replace him so I thought I will win even bigger margin. Long story short, the match ended up 2-0.

Sam as what happened to Marco, there are tons of save by the 'ghost GK'. I thought of complaining in the forum but I was winning the match anyway.