Lewis Hamilton was left reflecting on 'what might have been' on Sunday after producing a vintage 'world champion' show at the Spanish Grand Prix.
Hamilton recovered from running last following a first-lap collision to finish fifth after a stunning race for Mercedes at the Circuit de Catalunya where he has won a record six times.
The seven-time world champion was in 20th position and 35 seconds adrift after pitting with a puncture on the opening lap, but then surged through the field as the fastest car in the race won by world champion Max Verstappen in a Red Bull one-two.
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He would have finished fourth behind impressive teammate George Russell if not for a cooling problem that allowed Carlos Sainz to pass him for Ferrari on the closing laps.
"If I hadn't had that issue at the beginning, who knows where we would have been in the end?" he said.
"It's a horrible feeling being that far behind, but you have to keep your head up, keep pushing and hope for better."
After the clash with Kevin Magnussen's Haas, Hamilton volunteered to retire and save his engine, feeling that a points finish was not possible.
But Mercedes told him to stay out because they believed eighth was possible - and his surging drive earned him 'driver of the day' from the fans vote on the official Formula One website.
"They said I could maybe get to eighth and that doesn't feel like an impressive result, but at least I'd get into the points, but then to be fighting for fourth, I was so happy.
"The car felt great in the race. Our pace was closer to the top guys in the race, which is amazing.
"I was just really unfortunate at the start, to get the puncture I got, but I didn't give up. That's what we do, right?"
Russell finished third, after briefly holding the lead, to claim his second podium and sixth top five finish this season.
Team boss Toto Wolff heaped praise on both drivers as the team proved that their upgrades package had final solved the problem with 'porpoising' in an encouraging race.
He said Mercedes were now learning daily with their new package, introduced in Spain.
"We are literally learning by doing," he said. "These regulations have caught us off-guard, in a way, and step-by-step we're understanding what we need to do in order to bring performance back into the car.
"We've seen another big step this weekend, probably we halved the disadvantage to the front-runners, but there's still a way to go...
"With Lewis, we had probably the fastest race car. It was 15 seconds behind at the end and he caught all the way up - at times, he was the quickest. And that shows the potential that the car has."
He added: "Him showing this very good pace was important, not only for his morale, but also our morale. And who would have thought that he climbed all the way to fourth, before the problem came up.
"That looked like a world championship-winning race car that he was driving! And that would have not been possible in the previous races. That reminded me of last year and the years before when our car is really on the top of its game. And the driver!"