Russell looked nailed on for pole position after putting his car on provisional pole, but to everyone's surprise, Gasly had other ideas and snatched pole position from his and Mercedes' grasp.
Reacting to being pipped at the last second, Russell was frustrated that the promise from Saturday's final practice session hadn't translated into much of qualifying.
"It was a very scrappy session; I didn't feel quite as good with the car as I did in FP3. And then in Q3 we had a bit of an incident with Verstappen entering the lap; he wanted to get the tow and I ended up finishing my lap a second and a half behind him."
Despite his frustration, Russell was quick to give Gasly his flowers on a stunning pole that came against all the odds, especially considering Mercedes' dominance all day.
"Which wasn't ideal but takes nothing away from what Pierre achieved because, as you said, we were flying all day, quickest in Q1 and right up there from the beginning. I am happy for Pierre and, of course, disappointed for ourselves, as we want pole.
"But we are in a great position for tomorrow."
Asked whether Mercedes and the rest of the grid had taken Gasly's pace seriously enough, Russell admitted he didn't think Alpine were their competition even after the first qualifying session.
"They've looked strong all weekend. But we have often seen in Q1 that midfield teams have competitive laps and I didn't think much of it.
"They looked fast and Pierre obviously did a good job in Q1 but to be totally honest, we didn't think they were in the fight.
"It just shows what a great job he did and their team did to get the pole and pretty impressive."
Looking ahead to the race on Sunday, Russell fancied his chances of securing what would be a crucial win for him in his battle for the world championship.
He said: "We are definitely in with a shot of the win. It will be interesting fighting with Pierre; I think they have got a car that has some good straight-line speed.
''I don't really know where the fight is tomorrow, but confident I have got the pace to go for the win."
Finally, asked about how important a win is in the context of the title battle, Russell was keen to focus on his improved performance after coming back from the summer break.
"Every race is important, to be honest. I am more pleased with the performance in general. I have come back from the summer break and every lap, every session, I have been in the mix of the top three positions like I was at the start of the season.
"I had that tough run of form prior to the break where every lap wasn't even in the top five. So to come back, I am pleased to have found my feet again. Of course, the win is going to be very important tomorrow but I am more pleased about the performance."