Michael Schumacher has admitted for the first time that he is not enjoying racing following a disappointing start to the second season of his comeback.
The 42-year-old Mercedes driver finished 12th in the Turkish Grand Prix after another poor weekend.
Schumacher told BBC Sport: "The big joy is not there right now."
He won a record seven titles and 91 grands prix before retiring in 2006 but has been bettered by Nico Rosberg in 15 of their 23 races as team-mates.
Rosberg, 25, has also out-qualified his fellow German on 19 occasions.
Rosberg qualified third in Turkey, more than a second faster than Schumacher, who was eighth on the grid.
Schumacher was not helped by an opening-lap collision with Renault's Vitaly Petrov, for which he admitted he was at fault. The incident forced him into the pits for a new front wing.
Schumacher made three further stops for fresh tyres but never looked capable of getting close to the front-runners.
The result - allied to a retirement in Australia, a ninth-place finish in Malaysia and eighth in China - means he sits 11th in the drivers' championship with only six points.
Rosberg finds himself 10th on 20 points, while Red Bull's Sebastian Vettel leads the way on 93 points following his victory in Turkey.
"I told you before the race there was going to be some action and indeed I had lots of action," said Schumacher.
"I guess I was responsible myself to have the result that I had. With Petrov I guess it was mostly my mistake what happened there.
"I need to analyse it. It was a bit strange that suddenly we got together and I lost my front wing. The race was a given from there - lots of fighting, lots of action, but for nothing.
"From where we came [on the grid], going forward is always better than still having to defend backwards and mostly I was able to go forward."
Schumacher signed a three-year contract with Mercedes when he returned to F1 last year but BBC F1 chief analyst Eddie Jordan said it might be time for him to consider his future.
"I felt just a glimmer of sadness that here's a legendary person, who has been magnificent in all the years that he's raced, winning seven world championships," Jordan said.
"He's very human, he's very, very honest - he's clearly not enjoying it and the results are showing why he's not enjoying it. He has a couple of big decisions to make in the next couple of months."
But BBC F1 co-commentator David Coulthard cautioned against jumping to conclusions.
"He's not performing at the same level of his team-mate, that's a fact," stated the former Williams, McLaren and Red Bull driver, who raced against Schumacher for 12 years.
"The statistics show Nico Rosberg is getting more out of that car than Michael Schumacher.
"I don't think we should write Michael off by any stretch of the imagination - there's a lot of talent there - but he must be asking himself questions.
"I think the key thing is he's not enjoying it and to be perfectly open and honest with you there was an element of that for me at the beginning of 2008.
"I wasn't as competitive as I felt I should be, I wasn't enjoying the races as much as I used to and then that's the moment.
"It slowly builds until you look in the mirror and realise that feeling you've been having for a few weeks or months is the internal message. You can't hold back the clock."