The eight-times Grand Slam champion refused free entrance and insisted on paying for his own ticket, priced at US $30.
Youngster Querrey beat Bogdanovic 6-3, 6-2 to advance to the 24-player round-robin at the Las vegas Open.
Gilbert, who played a vital role in Agassi's comeback, is now Murray's coach and also has a wider coaching role with the LTA.
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