The Italian has shown impressive pace on his Gresini Honda so far this season, but has not been able to turn his speed into consistent results.
He has also received plenty of criticism for his aggressive riding style, particularly from defending champion Jorge Lorenzo.
And Simoncelli did his relationship with the Yamaha rider few favours when he lost control of his bike just four corners into last weekend's Dutch TT, taking Lorenzo down in the process.
Simoncelli eventually recovered to finish 10th but the Italian is hoping to put his error behind him at the sweeping Tuscany circuit.
"My first reaction when I came into the box after the race, as well as bitterness and disappointment, was that I had been a fool because I could have waited," he said.
"I made a mistake and it cost me dearly as well as involuntarily taking Lorenzo down too.
"I was sorry for him but more than that I was for myself because I had thrown away a big opportunity.
"It was probably my biggest mistake of the season, I have reflected a lot on it and it will help me to grow. Now I just want to look ahead to Mugello with calmness and motivation.
"Everybody is expecting big things from me and I have to repay that faith with a positive result that will put recent history firmly behind us.
"I am fast, I have found a perfect feeling with the bike and I am extremely determined to prove it in a race.
"There will be a lot of fans packed around the hills of Mugello and I don't want to, and cannot afford to, disappoint them. I love the track, it is one of my favourites and I won my first race here in 2008 in 250 before finishing second to (Mattia) Pasini in a great battle in 2009. I can't wait to get back on track."
Repsol Honda rider Dani Pedrosa returns from a three-race lay-off after breaking his collarbone in a clash with Simoncelli at the French Grand Prix in May, but veteran Loris Capirossi misses out on his home race after breaking two ribs in a qualifying crash at Assen.