Mark Webber has accused Romain Grosjean of being "borderline out of his depth in Formula 1" after witnessing the Frenchman's driving during the British Grand Prix.
Grosjean has found himself in the firing line following his antics during Sunday's race at Silverstone which saw him initially shown a black-and-white flag for unsportsmanlike driving in weaving in front McLaren's Carlos Sainz under braking.
The Haas driver was then forced to see the stewards for a repeat offence with Renault's Daniel Ricciardo, although was only handed a warning.
Grosjean defended himself by stating he left a car's width on each occasion, only for former Red Bull driver Webber to pick apart his argument.
Working as part of Channel 4's commentary team across the race weekend, Webber said: "I don’t think he understands the rules of engagement.
"He is moving around very late in defending. He is saying he is leaving a car’s width on the inside, which technically he is, but this weaving in the middle of the road at high speed… he has got to be even further across to show his intention earlier.
"I think Grosjean has a gross misunderstanding of what current grand prix racing is all about in terms of wheel-to-wheel combat."
Grosjean also cited Max Verstappen, who became renowned for moving across onto another driver's line in the braking zone of corners before cleaning up his act.
Webber added: "He’s mentioned how Max Verstappen was in the past, and that is in the past, we have moved on.
"He’s the chairman of the GPDA [Grand Prix Drivers' Association]. He should know the rules. For me, Grosjean is borderline out of his depth in Formula 1."
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