Toto Wolff has described Christian Horner as “a bit of a windbag” amid the ongoing row over flexible rear wings at the Azerbaijan Grand Prix.

The FIA is clamping down on how much movement is allowed from the rear wings after noting some teams were displaying excessive deflection at high speed before the wing returns to its usual position under braking. More stringent tests will be imposed from the next race in France but after Horner suggested the Mercedes front wing also deflects significantly and told Wolff to be careful how vocal he is, the Mercedes team principal hit back.

“Christian is a bit of a windbag who wants to be on camera,” Wolff (pictured at left, above, with Horner) told Sky Sports. “It’s about being punchy and it’s easy to be punchy when you’re top of the time sheet, but you should be a little more modest, I think.”

Wolff’s comments came before qualifying took place, after Horner had questioned the legality of the Mercedes front wing on Friday.

“There’s obviously been a lot of noise that Mercedes have been driving about the rear wings,” Horner said. “The bottom line is if the car complies with the rules, it passes the tests, it’s legal. The FIA comes up with the tests. That, if anything round here, looks maybe a bit worse than ours. I’d be more interested in seeing the front of the cars than the rear of the cars. So, you’re opening a complete can of worms. That’s why there are stringent tests in place that the cars need to comply with.

“A lot of noise has been made about the rear wing and a lot of revisions have had to be made. If you are picking on one end of the car, you need to look at the other. You can’t look at one part in isolation and say, ‘That set of rules only applies to that element on that car.’ You have to look at all areas. So sometimes you have to be a little bit careful what you wish for.

“I think if I was Toto with the front wing he has got on his car, I’d keep my mouth shut.”

After qualifying in third place — behind Charles Leclerc and Lewis Hamilton — Max Verstappen admitted he is enjoying the rivalry between the two team bosses.

“I think the weight division is a bit of a problem, the height and weight,” Verstappen said. “I’m all for a ring, even in F1, instead of penalties! That’d be great.

“It’s Formula 1 — there’s a lot of stakes involved, everyone wants to win. Everyone is competitive, it’s natural — a bit of fire behind it.”