Manager Simo Valakari believes St Johnstone will have to "earn our luck" against champions Celtic on Wednesday. "We need to do our football things so well, then at the same time, we need to earn our luck, because against Celtic, if you want to beat them, you need to be a little bit lucky in some moments," Valakari said. "You need to do your things so well that the luck favours you and that's kind of the thing that we tried."