Mark Webber says Sebastian Vettel has a tendency to buckle under pressure, recounting instances in the past when his former Red Bull team mate suffered a 'meltdown'.
The German driver is currently leading the drivers' championship as he bids - along with arch-rival Lewis Hamilton - for a fifth world title this season.
On the eve of Vettel's home Grand Prix in Hockenheim, nine-time F1 race winner Webber, who spent five seasons alongside Vettel at Red Bull, offered a reminder that the Ferrari driver appears to have a weakness that emerges when things don't go according to plan.
"[Vettel] does have flashes of a meltdown," Webber explained in a recent podcast with Formula 1's official website.
"Sebastian has had those and does have those. I think he has a plan and often these meltdowns are outside our normal routine of a grand prix. So: Safety Cars.
"Abu Dhabi [in 2012] he’s been off behind the Safety Car, hitting DRS boards," Webber remembers.
"We saw Azerbaijan. So it’s amazing how he has this maximum intense focus and concentration that he can do.
"Winning off pole off the front, breaking the DRS, that was his signature punch. He was deadly with that. But as soon as there was another complication that became a little more tricky."
In the podcast, the 2015 World Endurance Champion also recounted Vettel's blunder at the 2007 Japanese Grand Prix, when, driving for Toro Rosso, he ploughed into the back of Webber during the Safety Car period.
"There was podium for sure, which was unheard of," Webber remembered.
"Red Bull and a Toro Rosso on the podium together, this was like, never been done before.
"I pulled up beside Lewis [Hamilton] in the last sector saying, mate, the gap to the Safety Car’s ginormous.
"I was looking at him saying come on, the lights are still on, it’s not like we’re doing a restart, we’re still under Safety Car and he was pulling a long way back and mucking around so I pulled up beside him.
"The next minute, boom. Behind the Safety Car [Vettel] just absolutely harpooned the back of me, Sebastian and I went out. I know Seb was bawling his eyes out after that, he was shattered."
Webber was quick to call out Hamilton however, insisting the then McLaren driver was partly responsible for the collision.
"Lewis was really at fault to a degree. He was yo-yoing around. I think McLaren had some different brake material.
"It was a cold day, it was raining, it was a disgusting Grand Prix. I had food poisoning on the day, I was feeling pretty rough.
"We got through so much of the difficult part of the Grand Prix. All the aquaplaning. Fernando [Alonso] shunted which was rare. There was a lot of tricky moments throughout that race."
Further assessing Vettel's weaknesses, the Aussie revealed the German's discomfort when faced with the uncertain performance of his tyres in qualifying.
"He hated that. Hated that. Because it wasn’t bang, bang, German, what’s clear.
"It’s still a little bit open. Are the tyres ready on the first lap, maybe we’ll do two timed or one timed? He often hated that."
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