The world number one got off to a sluggish start dropping his serve in the third game as Ferrero came out with the clear game plan of attacking from all angles.
Federer twice asked the chair umpire to call for calm as spectators seated overhead were disturbing him.
"They were eating, it's not wrong but it is disrespectful for the people who are trying to watch the game," Federer said.
Monte Carlo Masters
Nadal claims first serve the key
22/04/2007 AT 17:17
"They should show more respect to the other fans. Of course, if you are down and you also have the noise, it's more upsetting."
"I never had the feeling I was totally out of the match. After breaking back, everything went well."
But Federer steadied the ship adopting new tactics to counter Ferrero's and broke back with a stunning backhand passing shot straight down the line.
The 25-year-old Swiss maestro looked firmly in control from that point on reeling off six straight games to take the first set and break at the beginning of the second set which left Ferrero struggling for ideas.
The one break of serve was enough for Federer to secure the win cruising through the remainder of the second set despite some defiant play from the 2003 French Open champion and wrapping up victory after 76 minutes with a backhand passing shot on his third match point.
"I'm very happy to go through because he is such a good claycourt player," Federer said.
"He has won the French Open, which is a feat I have yet to achieve. So I had to be very careful."
Federer will meet either two time defending champion Rafael Nadal or Czech Tomas Berdych in the final.
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Fed: Rafa forces me to improve
22/04/2007 AT 16:39
Monte Carlo Masters
Nadal wins third Monte Carlo title
22/04/2007 AT 12:17