Sunday is Mercedes' last hope of avoiding a first winless year since 2011 and the former champions are in a tight battle with Ferrari for second overall, with the Italians only four points behind.
Russell, who was also fastest in Friday's first practice and remains his team's most recent winner with victory in Brazil a year ago, lapped the Yas Marina circuit with a best time of one minute 24.418 seconds.
McLaren's Lando Norris was second fastest, 0.095 slower, with Australian rookie teammate Oscar Piastri third and Williams' Alex Albon fourth.
Verstappen was sixth and 0.735 off Russell's pace in a car he said was sliding a lot.
"The car is again bottoming, jumping," the Dutch driver said over the team radio.
"I don't know what is going on."
On Friday he had compared the car to a kangaroo, raising hopes that he may not have it all his own way in the finale.
Verstappen is chasing a record-extending 19th win of the campaign with Red Bull hoping to close out the year with 21 wins in 22 races.
Ferrari's Charles Leclerc, fastest in Friday's crash-interrupted second session, was fifth fastest with teammate Carlos Sainz last after crashing heavily on Friday and doing most of the final session on medium tyres.
Russell's seven-time world champion teammate Lewis Hamilton was 12th fastest, with Red Bull's Sergio Perez 11th.
McLaren are also in a tight battle with Aston Martin for fourth overall, only 11 points separating the two with millions in prize money at stake.
"We're definitely competitive," McLaren boss Zak Brown told Sky Sports television.
"Mercedes looks really good. Russell I think has more to come. You don't know what Red Bull was doing, I find it hard to believe they won't be right up there when it counts."
