Novak Djokovic insists his 2012 season has been "great" so far.
Perhaps unsurprisingly the Serb has been unable to replicate his incredible start to last year, when he won his first 42 matches, but he has won the only Grand Slam tournament so far in Australia.
Djokovic has suffered four defeats, the latest coming at the hands of Janko Tipsarevic in Madrid last week, but the world number one has put that behind him and is looking forward to the defence of his Rome Masters title this week.
Speaking in Rome on Sunday, Djokovic said: "This year so far for me has been great and I have already won a Grand Slam and Miami.
"Obviously I set high standards for myself with 2011, how it was in the first six months, but I never compare and I wanted really to focus on each and every tournament that I play in.
"Physically and mentally I am fine. I am where I wanted to be. I am number one in the world and I am winning Grand Slams. I love the challenge and I will now have to work harder to stay where I am."
Djokovic was speaking as the men's tournament got under way.
The big result of day one was Florian Mayer's win over Milos Raonic, one which set up a second-round meeting with Rafael Nadal.
In Madrid Raonic had pushed Roger Federer all the way to a final-set tie-break but on the slower surface in Rome his power game had less impact. Mayer won 7-6 (7/5) 6-4.
Former champion Juan Carlos Ferrero saw off Kevin Adnerson 6-4 7-5, while there were also wins for local stars Paolo Lorenzi and Andreas Seppi, as well as Viktor Troicki and Mikhail Youzhny.