have a card up your sleeve idiom
有锦囊妙计，有一张王牌，留有一招
to have an advantage that other people do not know about
England have definitely been the weaker side, but I think they've still got one or two cards up their sleeve. 英格兰队无疑处于弱势，不过我觉得他们还有一两张王牌未打出来。