The sensational return by the 29-year-old from Lithgow in New South Wales comes just a month after Canada's Jonathon Power topped the list in January - four and a half years after last being world No1!
Palmer, who first established a four-month reign as world number one from September to December 2001, has enjoyed a highly successful past twelve months – which he crowned last month by winning the Windy City Open in the USA, where he beat Power in a dramatic five-game final in Chicago.
Showing impressive consistency in 2005, Palmer reached five PSA Tour finals - including the Pakistan Open, US Open, Qatar Classic and World Open - and triumphed in the Kuwait Open in March.
Power slips to two in the new list, ahead of Egypt's world champion Amr Shabana at three and Australian Anthony Ricketts at four.
While Finland's Olli Tuominen moves up one place to celebrate a career-high No 13 ranking, Egypt's Mohammed Abbas returns to the top twenty at 20. In three appearances in PSA Tour events in January, the 25-year-old from Cairo reached the quarter-finals of the Canadian Classic and the semi-finals of the Dayton Open in Ohio.
Following his sensational success in the Dayton Open where he upset three seeds to reach the final as a qualifier, Egypt's world junior champion Ramy Ashour records a career-high No30 ranking in the new list – taking the 18-year-old ahead of his older brother Hisham Mohd Ashour for the first time!
1 [4] David Palmer AUS
2 [1] Jonathon Power CAN
3 [2] Amr Shabana EGY
4 [3] Anthony Ricketts AUS
5 [5] Thierry Lincou FRA
6 [6] James Willstrop ENG
7 [7] Peter Nicol ENG
8 [8] Lee Beachill ENG
9 [9] Nick Matthew ENG
10 [10] John White SCO
11 [12] Gregory Gaultier FRA
12 [11] Karim Darwish EGY
13 [14] Olli Tuominen FIN
14 [13] Mohd Azlan Iskandar MAS
15 [15] Ong Beng Hee MAS
16 [17] Stewart Boswell AUS
17 [16] Shahid Zaman PAK
18 [19] Graham Ryding CAN
19 [18] Alex Gough WAL
20 [24] Mohammed Abbas EGY
For full list – see www.psa-squash.com/