Heikki Kovalainen says a wager laid down by then McLaren teammate Lewis Hamilton at Spa in 2009 was just another indication of the Britain's outstanding talent.
In the latest episode of F1's 'Beyond the Grid' podcast, Kovalainen recalled how Hamilton had challenged the Finn to run faster than him through the daunting Raidillon corner on the pair's first lap out of the pits in practice.
"We were at Spa, and the first practice was just about to start, and I think Lewis came to me and said: 'Would you like to do a bet, just on the out lap, that who goes faster through Eau Rouge straight out of the box?'" the Finn remembered.
"In those days it wasn't like easy flat out straight out of the box on Friday morning. And I said, 'Yeah, yeah, we'll do that'.
"Then he just went with the right leg straight and went flat out the first lap. I had a tiny lift and I lost the bet. But that was the kind of thing that he was...
"I kind of knew that that's lost money for me. I was never gonna win that. So yeah... he's got unbelievable fighting spirit."
Kovalainen spent two seasons alongside Hamilton at McLaren, out-qualifying the Briton nine times in 35 races but finishing well adrift from the latter in the championship standings in 2008 and 2009.
But the need for Kovalainen to consistently pull out all the stops to match or beat his teammate eventually took its toll on the Finn's stamina and force.
"He was just that tiny bit faster all the time, and I had to stretch, every session," he said.
"It was straight from the winter test, you know, I was always like... I had to stretch to match him or be ahead of him, like an average lap wasn't good enough.
"And when you've done that for a year and a half... I kind of run out of energy.
"In the second half of the second year, 2009 in McLaren, it's fair to say that I drove below my own ability even," he added.
"Rather than focusing on my own race and my own results, and trying to get close to Lewis, I started to overdrive. I got frustrated and, in fact, the gap just got bigger and I made some mistakes.
"I think the reason why that happened during that second half of 2009 was because I had to stretch all the time. And when you're stretching for too long time, you run into a wall at some point."
Despite being eclipsed by Hamilton during his time at McLaren, Kovalainen is happy to have gone head-to-head with the six-time world champion.
"I think it's just his pace was just a tiny bit quicker consistently," he said.
"I don't have any trouble admitting it. He is one of the greatest, if not the greatest driver. I'm glad I went against him.
"But at that point of my career, it was also quite detrimental for my career. I had a momentum, but I wasn't able to keep the momentum going with Lewis as my teammate."
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