Michael Schumacher admits he heads into the unknown this weekend, even though he is a five-times winner of the Monaco Grand Prix.

It is the unpredictable nature of the Monte Carlo street track that is always such an attraction for any driver, young or old, and no matter their level of experience.

It is why the 41-year-old Schumacher, despite his success and the fact he has competed in 15 races around the principality, has no idea just what he will encounter over the next two days.

"You have years and days where things come together and you seem to pull out this extra bit and you look unreal, you do a phenomenal job," said Mercedes star Schumacher.

"But then there are moments when you put the same effort in, but things don't happen, and you don't know why.

"You can't understand why it was so different to when you drove a car before and you could do it then.

"So we will see how this weekend is going to go, how this car will suit the track and how much I will find the set-up, the rhythm and have a clear track at the same time.

"If you want to nail it here there is no margin for error, you have to get close to the wall, to flow around the track, to time it all perfectly right."

On that basis, Schumacher is refusing to rule out the prospect of victory and joining Ayrton Senna as the most successful driver at Monaco with six wins.

Although Mercedes do not appear to have a car that can win races, and Schumacher's best finish this season was fourth in Spain on Sunday, the unknown factor comes into the equation again.

"After what happened in Barcelona there's probably no point talking about winning because we were quite a margin behind," added the German, who finished over a minute adrift of race winner Mark Webber.

"But who knows what this track will offer to us."

Much will depend on today's qualifying session, which like the track itself offers so much uncertainty given the increase in the field to 24 cars this season.

Lewis Hamilton has warned it "could be a disaster," whilst Jenson Button has suggested there will be angry scenes and drivers calling for penalties.

Others have also spoken of their concerns, and Schumacher is no different.

"As drivers we had suggested we split Q1 into two groups and give each 10 minutes," said Schumacher.

"But some team bosses felt they would rather have the chaos and take the profit than have a reasonable clean qualifying.

"So that's what it is and what we have to deal with and let's see who suffers or not."