fade into insignificance

To begin to seem unimportant when compared to something else. My good grades faded into insignificance once my sister got home with news that she would be the lead in the school play. Yeah, don't say anything about our engagement, OK? I don't want to your brother's graduation to fade into insignificance the moment it's over. I'm telling your mother right now! This is big news—and I don't want it to fade into insignificance as the day goes on.