Math Question on Probabilities

[John Weber]

Roger Federer, who many say may be the greatest male tennis player in history, has now reached the semifinals (final 4 of 128 players) in 18 consecutive Grand Slam tennis tournaments.

All other things being equal (i.e. a 50% chance of winning each match), what are the odds of someone duplicating that feat?

Not being a math whiz myself, I would say the odds are 1 over 32 to the 18th, whatever that number happens to be.