West Brom skipper and goalkeeper Scott Carson must wait to find out if he will be axed for Saturday's home Premier League clash with Blackpool.
Carson has been below his best in recent weeks and his glaring error led to Fulham's opening goal in their last league outing 10 days ago - a 3-0 defeat at Craven Cottage.
Now Di Matteo must decide whether the time has come to make a change or keep faith with Carson - but he will take his time.
"I thought Boaz did well on Saturday and I'll have a tough decision to make," Di Matteo. "I haven't made the decision yet but I will later when the time is right.
"I want to allow myself time to think about it and see how training goes, like with any other players. I will talk with Dean Kiely (goalkeeping coach) but ultimately I will make the decision.
"We need to look at who is in the best shape or form to win a game for us.''
The Baggies cannot afford anymore avoidable slip-ups as five successive league defeats have plunged them towards the relegation zone.