Nico Rosberg had 'complete lack of confidence' in Monaco Grand Prix

Rosberg cited brake issues as a potential cause for his seventh-place finish, while Mercedes motorsport boss Toto Wolff suggested it was more to do with a failure to get sufficient temperature into the tyres.

Rosberg was forced to let by team-mate Lewis Hamilton in the rain-hit early laps, with the reigning world champion going on to clinch his first win of the season.

Asked whether it was painful to let Hamilton past, Rosberg replied: "It was more painful with the feeling I had in the car, that was the worst one.

"There was a complete lack of confidence in those conditions, and around Monaco that is not a good feeling to have.

"I had to stay well away from the limit because otherwise I would have been in the wall.

"So that was the most painful because at that point I realised with that feeling in the car I wouldn't be able to fight for the win."

Asked how he was so short of confidence and pace, Rosberg said: "We are looking into it and trying to understand it. There are already a few things that have come up.

"What we do know is there was a brake issue with the temperatures, quite a large one.

"For sure it caused problems, but it"s too early to say whether that was all of it, or to come to any definite conclusions at the moment. It"s going to take a bit of analysing."

Even on the final lap, with the rain beginning to fall again, Rosberg had issues as Force India's Nico Hulkenberg passed him on the line to claim sixth.

Rosberg explained: "I was on the ultra-soft and he was on the soft. He had loads of rubber left and I had no rubber left. He had more temperature, and with the rain mine were stone cold."

From Wolff's perspective, it was the tyres that were of most concern.

"Somehow over the weekend we weren"t able to put them in the right window," he said.

"It looked like at the beginning [of the race] we were suffering the same, and [Daniel] Ricciardo was just pulling away.

"The reason, we believe, is tyre temperature. We looked at the situation for many laps and it lost us quite some time.

"We hoped the tyre would switch on, but Ricciardo was 10 or 11 seconds gone.

"It was almost a damaged car, and this is why we decided to make that call [for Rosberg to let Hamilton by].

"We debated it for quite a long time because it's not what we've done in the past, but it was clear there was a problem on the car."