Lyons declared fit, Tawake misses RWC August 20, 2007
Lyon's RWC appearance was in doubt when he underwent surgery for deep vein thrombosis which saw catheter inserted in his groin to relieve blood clots around his calf last month.
Tawake had been bracketed in for replacement pending medical official's decision to clear Lyon for travel.
However, the number eight has been cleared of blood-clotting concerns and will fly out with the Wallabies next week for the RWC.
Lyons will still have to administer three injections daily during the World Cup to keep his health in check.
"It's a big relief," Lyons told the Daily Telegraph.
"I was optimistic to start with but then after the first visit to hospital it blocked up again. I was thinking I might be in a bit of trouble."
The Wallabies will be fielding the most experienced team at next month's tournament.
The Australians have more on-field experience than any other team in Test history and more than any other starting World Cup team in the 20-year history of the tournament.
With 73-Test fullback Chris Latham and 53-Test winger Lote Tuqiri returning to the full-strength side for the September 8 match against Japan at Lyon, the Wallabies will boast an aggregate 795 caps if David Lyons is selected at No. 8.