When fully fit, the top-seeded Haas can still compete with the very best on the tour and he confirmed his form and fitness against America's Wayne Odesnik, needing just 55 minutes to reel off a 6-2 6-1 victory at the Las Vegas event.
"With injuries, I lost probably three or four years of my career," Haas, ranked 12th in the world, told reporters.
"I always felt I wanted to end this on my terms, like when the mind is not there anymore or physically I can't do it anymore. I just want to continue and enjoy."
Haas, who once rose as high as number two in the world, never faced a break point during his lopsided win and is looking to win the tournament for the first time since 2006.
The 32-year-old Australian, who captured this title back in 1999, would have been delighted with his display, particularly as the eighth seed's compatriot and golf legend Greg Norman was one of the spectators.
Isner, seeded two, needed every one of his 20 aces to prevail and was unable to crack Russell's serve in the first two sets before breaking his opponent twice in the decisive third.
Japan's Nishikori outlasted Portugal's Gastao Elias 6-1 5-7 6-2 while South Africa's Anderson rallied past American Tim Smyczek 4-6 6-1 6-3.
3-Kei Nishikori (Japan) beat Gastao Elias (Portugal) 6-1 5-7 6-2
Rhyne Williams (U.S.) beat Alejandro Falla (Colombia) 6-3 4-0 (Falla retired)
Ivo Karlovic (Croatia) beat Samuel Groth (Australia) 7-6(4) 6-3
1-Tommy Haas (Germany) beat Wayne Odesnik (U.S.) 6-2 6-1
Ryan Harrison (U.S.) beat Lu Yen-Hsun (Taiwan) 4-6 1-0 (Lu Y H retired)
Marinko Matosevic (Australia) beat David Goffin (Belgium) 6-2 6-4
Steve Johnson (U.S.) beat Mikhail Kukushkin (Kazakhstan) 6-4 6-3
Teymuraz Gabashvili (Russia) beat Matthew Ebden (Australia) 2-6 6-3 6-2
4-Kevin Anderson (South Africa) beat Tim Smyczek (U.S.) 4-6 6-1 6-3
Marcos Baghdatis (Cyprus) beat Jiri Vesely (Czech Republic) 3-6 6-2 6-1
Dudi Sela (Israel) beat Alex Bogomolov Jr (Russia) 6-0 6-2