Paul Charnley's side were at home to Boldmere St Michaels and won 5-2 in a third round tie.
Tom McGuire put Sphinx ahead in the tenth minute only for Ian Smith to equalise in the 28th minute.
A Thomas Stevenson free header put Boldmere ahead in the 49th minute.
Sphinx hit back with two goals inside a minute. Tom McGuire shot home from the right in the 55th minute and just under a minute later,Covsupport sponsored Adam Knibbs stabbed in.
Substitute Chris Harris kept the Sphinx support warm and happy when he scored in the 71st minute, stabbing home a McGuire cross and in the last minute was on hand to finish off another neat move.
Former Sky Blue John Williams was on the bench for Boldmere but did not come on.