Interim manager Benitez claimed the Stamford Bridge decision-makers who have halted contract talks with the England midfielder had no doubt about "his condition, his levels, his quality".
His wage, age, 34, and recent injury record might come into consideration when debating a new deal but Benitez told BBC Sport: "For sure, he's a fantastic player, a great professional - there's no doubt about this. Also, when I talk to the people in charge, they are telling me the same, so nobody has any doubt about his condition, his levels, his quality. So the decision could be analysing different things, not just the quality of the player."
Lampard insisted he had "two or three years at least" left to give as an elite footballer - even if Chelsea appeared to think otherwise.
He admitted on Thursday his glittering career with the European champions could be drawing to a close after revealing he was not in talks with them over a new contract to replace the one that expires next summer.
Lampard appeared resigned to his fate after helping Chelsea into the Club World Cup final in Yokohama, coming off the bench against Monterrey for his second appearance since recovering from a troublesome calf problem.
That compounded an injury-hit 2012 but Lampard made it clear he had more to give.
"I feel like I have two or three years, at least, in me at the top level," he said.
"It is not for me to decide on this one. It's up to the club.
"Whatever happens, I have had a great time at Chelsea. I am determined to play a few more years and see what pans out in the near future."
Corinthians sharp-shooter Paolo Guerrero has predicted the Brazilian side will lift the Club World Cup if they play their own style of soccer against Chelsea in Sunday's final.
The Peruvian, who headed the winner in an unconvincing 1-0 victory over Egypt's Al-Ahly in their semi-final in Japan, said European champions Chelsea were vulnerable.
"Everyone knows Chelsea is one of the world's great teams," Guerrero told reporters in Yokohama on Friday. "It is a final everyone in Brazil, every Corinthians fan is waiting for.
"We know it will be very difficult because they have different training, a different game," added the former Hamburg forward.
"Corinthians have a lot of quality too and we have to play our own game."
Corinthians won the first edition of the FIFA tournament in 2000 but Chelsea, who comfortably beat Mexico's Monterrey 3-1 on Thursday, will start as favourites.
They also became the South American Libertadores Cup's first unbeaten winners since 1978 this year, conceding just four goals in 14 matches, so will be no pushovers for Chelsea.
"We know it will be a tough game," said Guerrero. "But we know that finding the net and playing our type of game will get us the world title.
"We have a lot of ways of changing tactics so it will be difficult for Chelsea too."
A clash of styles in Sunday's final should make for a more absorbing encounter than in recent years, European sides having rolled to victory in the last five finals.
"It is two different styles," agreed Guerrero, one of several danger men Chelsea will have to keep a close eye on to avoid an ambush.
"Corinthians press well and play neat football. Chelsea play well and they have very fast players but possibly they're weaker pressing opponents. With our speed we can take advantage."
After taking four games to register a victory under interim manager Rafael Benitez, Chelsea have tightened up in defence and have been looking to press higher up the pitch.
Three wins in a row, scoring 12 goals in the process, have given Chelsea fans unhappy at Benitez's appointment after last month's sacking of Roberto Di Matteo reason for optimism.
"To win the way we won was very important," said Spanish playmaker Juan Mata, who scored Chelsea's opening goal against Monterrey.
"We came here to win the trophy and become the world champions. We have been focused on scoring more goals and this has given us real confidence for the final."
The Corinthians players, expected to be cheered on by at least 15,000 fans who made the trip from Brazil, looked relaxed at training on Friday despite the pressure on them.
"This is a very important moment for my career to win a world title," said Guerrero. "Every player dreams of a final like this against a great European team like Chelsea.
"That's why I have absolute concentration now and I'm calm about Sunday."
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