Mercedes boss, Toto Wolff describes the W13's lack of performance at Paul Ricard as being like a "slap in the face".

The Austrian was talking after Lewis Hamilton claimed fourth on the grid for the French Grand Prix, albeit 0.893s off the pace.

A weekend which had begun with Damon Hill predicting Hamilton leading a historic 1-2 for the German team at his 300th outing, saw Mercedes totally unable to get on terms with the title protagonists.

After a disappointing outing on Friday, Hamilton oversaw a raft of changes on his car overnight, resulting in the seven-time champ actually losing ground.

Speaking at the end of a frustrating day on in which his drivers were almost spectators, Wolff couldn't conceal his frustration.

"We were slowly, but surely working our way back to the front-runners," he said. "There were good signs in Silverstone and then we went to Austria, a track where we are normally not competitive at all, and we were close.

"Then we brought quite a nice update package to Paul Ricard, a track that's smooth, and off we go to hunt them down, and then... no performance, like, no performance.

"We can't figure out," he admitted. "We can't figure out what went wrong. We experimented with rear wings, with almost the biggest we have, which Lewis described as dragging a parachute behind him in the morning, to a smaller version that makes us lose too much speed in the corners.

"Then we were experimenting with tyre temperatures and you can see we are now 0.7s to Verstappen - the Ferrari lap is a bit of an outlier with the tow here with Sainz - but if you would told me we would be 0.7s to 0.9s off the pace ahead of the weekend then that would be a bit of slap in the face."

Asked if there is a fundamental problem as Mercedes considers the trade-off between downforce and drag, Wolff said: "I wouldn't know whether it is the aero per se, but we are seeing in one session we are totally uncompetitive in the first sector and then in Q3 we are the best in sector one and the opposite in the last sector.

"Clearly there is something happening, whether it is wind affected or tyre performance, where the car is on the edge and between hero and zero there is a super fine margin that we don't understand."

"Position wise, I'm really happy with my qualifying session if I'm really honest," said Hamilton. "My last lap was great, I finished it and I was like 'that was an awesome lap'. But still nine tenths off the guys ahead.

"I'm not really sure why that gap's got bigger over the last two races," he admitted. "They're kind of in their own league I would say.

"I came here this weekend hoping that we were going to be within three-tenths off them and we're a second off. With the three-tenths, I was hoping that the next race we can close that a couple of tenths more and we'd be in the fight in Budapest. But if it's anything like this, then it's going to be a while. But it's possible.

"Considering I missed P1, which definitely does put you on the back foot, I'm really happy with the progress that I made," he insisted.

Asked to clarify where he is losing out, Hamilton puts it down to straight-line speed.

"In the last lap, the first sector was just as quick as the guys ahead," he explained. "And then it's all down the straights, we lose a lot down the straights. I don't know what time it is, but it's at least half a second probably just on the straights.

"Then all through that high-speed section, the last few corners, they're pulling chunks off us. It's like they have less drag and more downforce in all the corners.

"The last sector was like six, seven tenths or something. It's just crazy. A lot of it's just full-throttle. So some of it's just that drag but for some reason they're able to go much quicker through the high-speed corners than us. I don't understand it. But we'll just keep working away."

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