Lewis Hamilton believes Mercedes' improvement from the final practice session to qualifying was the biggest jump in pace they have ever been able to make.
Both Hamilton and teammate Valtteri Bottas were off the pace all weekend and were not expected to challenge for pole position. However, Hamilton managed to get the car into a good operating window to qualify in second place, ahead of championship leader Max Verstappen.
"Honestly, it's one of the greatest feelings for us," Hamilton told RacingNews365.com and other select members of the press.
"For the difficult experience we've gone through with being out of the top 10 all weekend and really struggling to understand and extract performance from our car it feels fantastic.
"I'm just incredibly proud of the whole crew, for the amazing work, for everyone to be open minded. We've made a lot of changes and there's been so much work back at the factory overnight and even today."
Hamilton was third in the final practice session but that was mainly down to a substantial slipstream at the end of his lap. On track, the car still looked very edgy with Mercedes being unable to work out how to get the tyres into the optimal working window.
"We discovered something at the end of FP3 and continued to push down in that direction and it paid dividends," said Hamilton. "The car was literally night and day.
"Practice 2 and Practice 3 were pretty much a disaster, we did some changes overnight which didn't rectify the issue. In FP3 we tried a few different things and then tried something right at the end, just with the setup and it unlocked the potential a little bit.
"It really just about getting the tyres to work. We just couldn't get our tyres to switch on, like the others generally can, so the difference was all of a sudden the tyres started working, and we were back in the game. Then it was just about putting the laps together."
Hamilton trails Verstappen by four points in the Drivers' Championship and it looked like he was set to lose yet more ground in the race for the title. Now, he is in a position to capitalise on Red Bull's average Saturday in Baku after an emotional 24 hours for Mercedes.
"It's really kind of hard to explain the emotions that have come through for the past day," said Hamilton. "It was difficult for us to understand why we're in the position we're in because we're trying lots of different things, and we don't always get the results that you're expecting to get.
"No matter what we were doing, we couldn't really fix it so from my point, I'm pushing the guys, 'I want to try this, I want to try that'. Naturally when you do that, I had a lot of anxiety because you don't know if you're going to get it right or get it wrong."
Hamilton used a low-downforce front wing which gave him one of the highest speeds in the speed traps in qualifying. On a track where overtaking is possible, it could prove crucial in the race on Sunday against Leclerc and Verstappen.
"I think we've got the right balance with the wing," commented Hamilton. "You could always say you could have a slightly better balance, but it did the job in qualifying.
"I think for race pace we were we weren't as quick as the Red Bulls but we were in the mix. I think on Sunday we should be close to these guys."