(ii) A captain may change the nomination of the singles players for the third and fourth singles matches on the following conditions:
Notice of such change to the third singles match is given to the Referee at least one hour before the start of play of the third singles match.
Notice of change with respect to the fourth singles match is given no later than ten minutes after completion of the third singles match.
If, one hour or less before the commencement of the third singles match, one of the players, in the opinion of the Referee, is ill or injured, he may sanction the substitution of that player by another player nominated for the Tie.
(iii) Any substitute nominated under section (ii) above for the third or fourth singles match must be selected from among the players nominated for the Tie and who has not competed in the first or second singles matches.