Two-time bracelet winner Mueller started the day just outside the top 10 but finished well inside it, bagging up 2,396,000 to sit second overall behind Cyrus Farzad at 2,600,000.
Mueller and Farzad are the only two players in the field to crack the 2 million-chip mark.
Madsen, the 2006 WSOP Player of the Year and also a two-time bracelet winner, made his move from farther back in the pack.
Starting the day with 250k in chips, Madsen quietly ran his stack all the way up to 1,675,000 and will start Day 4 today fourth overall.
Stephen Graner (1,882,000) and pros Max Steinberg (1,125,000) and Ali Eslami (1,065,000) round out the top six.
Cheong Holds the Line, Koon Retreats
One of the Day 2 chip leaders, former November Niner Joseph Cheong hung on to the chips he had but didn’t make much progress on Day 3, finishing with roughly the same stack to head into Day 4 near the bottom of the pack in 13th.
Jesse Martin (931,000) and Sam Barnhart (756,000) will also return for Day 4.
Pro Jason Koon, a WPT “Player to Watch” for this season, narrowly missed the final two tables as he busted out in 19th for $13,400.
Also busting out shy of the final 18 were Yevgeniy Timoshenko (25th - $13,400), Erick Lindgren (33rd - $11,100), Isaac Baron (34th - $11,100) and Dwyte Pilgrim (36th - $11,100).
Action picks up today at the Bicycle Casino at 1 pm local time and will go until the final table of six is set. $500,000 awaits the winner and $293,490 for the runner-up.
Follow along with the WPT Live Updates here.
The final 18 players and chip counts:
1. Cyrus Farzad - 2,600,000 2. Greg Mueller - 2,396,000 3. Stephen Graner - 1,882,000 4. Jeff Madsen - 1,675,000 5. Max Steinberg - 1,125,000 6. Ali Eslami - 1,065,000 7. Jim Willerson - 988,000 8. Jesse Martin - 931,000 9. Ramzi Srour - 838,000 10. Sam Barnhart - 756,000 11. Alan Myerson - 704,000 12. Josh Hale - 680,000 13. Joseph Cheong - 580,000 14. Raouf Malek - 505,000 15. Efren Abustan - 451,000 16. Art Alaniz - 405,000 17. David Marshall - 400,000 18. Antonios Roungeris - 337,000Visit www.pokerlistings.com