(Reuters) - For 55 minutes Nigeria were comfortably keeping France at bay, but then Blaise Matuidi planted his studs on Ogenyi Onazi and their World Cup ambitions were as damaged as the midfielder's ankle.

Matuidi was fortunate to receive only a yellow card after his late lunge on the Lazio man's ankle arrived long after the ball had been played.

The Paris St Germain midfielder, who had protested every decision awarded against him in the last 16 clash, knew right away he was in the wrong and successfully pleaded for mercy from U.S. referee Mark Geiger.

Nigerian players and management were clearly aggrieved at what they saw and pointed the finger at Geiger, who let a number of strong tackles go unpunished at the Brasilia national stadium on Monday.

"I am not happy about it but he is the one who decides what goes on the pitch," Nigeria coach Stephen Keshi told reporters.

"He decides what happens on the field but I am not happy with the officiating.

"On two occasions Onazi had very bad tackles. He's out now probably for weeks. This is the first time in my life I speak about the referee but it wasn't good."

It took Keshi almost five minutes before he replaced Onazi with Reuben Gabriel and the incident clearly hurt his team.

Shortly after, France hauled off the ineffectual Olivier Giroud in favor of the speedy Antoine Griezmann, but he too was fortunate to escape any punishment after a studs up tackle on Efe Ambrose.

Geiger saw nothing in the incident as Griezmann broke and put Benzema through only for the ball to be hacked off the line, the first of several chances the French created against the reshuffled but not reorganized African champions.

Nigeria defensive midfielder John Obi Mikel, without the composed 21-year-old Onazi alongside him, struggled to protect his backline as the pressure racked up.

The French zipped the ball around quicker, space was found and a goal always looked likely with Nigeria struggling to cope with the movement of Mathieu Valbuena and Griezmann and bursts by Matduidi and Paul Pogba.

The Nigerians had been grateful to Vincent Enyeama for a number of sharp saves before his error handed Pogba the easy chance to header France in front and set up a last eight clash.

Nigeria, though, were left thinking of what might have been.

Playing against 10 men for the final 30 minutes would surely have aided their bid for a first quarter-final appearance.

"Was the referee too lenient? It depends what side of the fence you are standing on," French coach Didier Deschamps said.