Really hope he is given a chance tomorrow, but more likely to be Romero.
Why would we play keeper like Romero who most likely cant speak English - would struggle coordinating defense, is new to the league and to his teammates and in fact just arrived and didn't feature a game for us? Let alone handling crosses from trippier, Erricksen and Kane on headers.. This would be a hug risk by Van Gaal but strange things had happen under his management so I wouldn't be that surprised.
Other options are - out of favor Valdes who played for reserves, struggled in his first game and would struggle another. He's shit goalkeeper who didn't have a club for year or so and was injured, he would be even a worse option than Romero IMO, really don't rate him and Van Gaal probably took him back to get more money for him when we eventually sell him.
Lindegaard didn't feature at all last three seasons, he's decent goalie but it is clear that Johnstone is now ahead of him as he got more gametime in preseason and showed great potential.
Johsntone has more experience with English football than the three altogether I guess. Let's put him in cage and see what happens. It might be his lifetime chance. It's also a home game and he's our player he will be motivated even more rather than nervous I feel.