Her New Zealand team-mate Cecilia Cho, who plans to turn professional in March, remains as the world number three following a disappointing showing at the Australian Amateur.
Cho, who had finished runner up at the event previously, was soundly beaten 5 and 3 in round one.
The two-time New Zealand Amateur champion remains only just behind Williams on 1738.33 average points.
Wellington's Julianne Alvarez has climbed 12 places to 106 in the world, Auckland Wenyung Keh jumped 13 places to be 109 and Sarah Bradley slipped 21 places to be 151.
Zoe Brake (211), Kristin Farrell (224) Chantelle Cassidy (228) and Emily Perry (262) are the next highest ranked Kiwis.
On the men's side, Masterton's Ben Campbell slips two places after bowing out in the second round of the Australian Amateur but he remains the New Zealand number one by some distance.
The 21-year-old, who is based in Melbourne and has been as high as eighth in the world, is now ranked 55th best golfer by the R and A rankings.
Campbell, who finished fourth in the individual standings of the 2010 Eisenhower, is looking for a big 2012 in the lead up to the World Teams Championship in Turkey.
Southland golfer Vaughan McCall, who finished fifth in qualifying for Australian Amateur only to lose in the opening round, climbed 43 places to 168 in the world.
New Zealand Amateur champion Mathew Perry also moved up in the standings by 51 spots to 191.
Blair Riordan, who knocked out Campbell in the second round and then lost in the third round on the 20th hole to Ruben Sondjaja, is rewarded for his good tournament and he jumps 91 places to 228.
Auckland rep Sam An, who wasn't at his best in Melbourne while he was battling illness, drops 20 places to 261 in the world.
