A string of errors put world number two Andy Murray out of the Monte Carlo Masters on Thursday, when he lost 6-1 6-2 to Swiss Stanislas Wawrinka in the third round.
Fourth seed Tomas Berdych was also beaten at the first big claycourt event of the season, while Rafael Nadal calmly continued his bid for a ninth consecutive crown with a 6-2 6-4 victory over Philipp Kohlschreiber of Germany.
Briton Murray, who has repeatedly said he needed time to find his feet on the red clay, looked frustrated on court and picked up only eight points on serve in the first set.
"I made a lot of mistakes - 24 unforced errors is far too many...that's were half the points went," Murray told a news conference.
"I started hitting the ball shorter, then he was able to dictate the play," he added.
The 17th-ranked Wawrinka, who had won their two previous encounters on the surface, reached the quarter-finals for the second year in row and will now face Frenchman Jo-Wilfried Tsonga, who overwhelmed Austrian Juergen Melzer 6-3 6-0.
Czech Berdych also struggled with his serve after having had to recover from a break down in each set in the second round to get past Spaniard Marcel Granollers.
A semi-finalist last year, Berdych was broken four times overall and barely managed to unsettle the 32nd-ranked Fognini, who also beat him in the first round here in 2009.
Fognini will now face seventh seed Richard Gasquet of France who beat Croatian Marin Cilic, seeded nine, 7-5 6-4.
Reigning champion Nadal notched up his 44th win in a row in the principality and set up a quarter-final encounter with 34th-ranked Grigor Dimitrov of Bulgaria.
German Kolschreiber did not pose a big threat to Nadal, who had taken a month-long break to rest his knee after making an impressive comeback to the tour from seven months out injured by winning three titles including the Indian Wells Masters last month.
The Spaniard pleased the big crowd with a solid display on the sun-baked Centre Court that has been his stage since 2005.
"The match started with a lot of intensity for both of us and I was able to have the break. After that, I was comfortable with my serve," Nadal said.
"The second set, I think the intensity went down a little but I was in control," he added.
Dimitrov, who at 21 is making his debut in the Monte Carlo main draw, beat German Florian Mayer 6-2 6-4.
World number one Novak Djokovic, who is playing despite an ankle injury, was due to face Juan Monaco of Argentina later.