It is possible, and not unheard of, to make a move which causes your opponent to have a line of five markers in a row. When more than one line is made in the same move, the player who just moved resolves her own lines (if any) first, and then the other player resolves his lines (if any) before making his next move. Lines are resolved one at a time, so if a single marker is shared by two lines, only one of those lines may be resolved (but the player chooses which).