Arsene Wenger is a "specialist in failure", according to Jose Mourinho.
The Chelsea boss was responding to the Arsenal manager's claim that other Premier League bosses are playing down their title chances because they "fear to fail".
Chelsea hold a one-point lead over the Gunners at the top of the table.
Mourinho said: "If he is right and I am afraid of failure it is because I didn't fail many times. Eight years without silverware, that's failure."
Under Wenger, Arsenal have not won a trophy since the 2005 FA Cup.
"He's a specialist in failure," continued Mourinho. "If I do that in Chelsea, eight years, I leave and don't come back."
The Portuguese manager, who won the Premier League twice in his first spell as Chelsea manager between 2004 and 2007, has won league titles in four countries, as well as the Champions League with Porto and Inter Milan.
This is not the first time Mourinho has criticised Wenger, the Blues boss having described the Frenchman as a "voyeur" in 2005 after his rival questioned Chelsea's transfer policy.
"He likes to watch other people," said Mourinho in October 2005. "There are some guys who, when they are at home, have a big telescope to see what happens in other families.
"He speaks, speaks, speaks about Chelsea."
Former England striker and Match of the Day presenter Gary Lineker said Mourinho had gone "over the top" with his latest remarks.
"Mourinho is out of order and wrong with Wenger comments," Lineker wrote on Twitter.
"He's won trophies galore all over the world, playing delightful football.
"Yes, Wenger hasn't won anything for a number of years, but he hasn't, until very recently, had the budget of others. Club is in great shape."
Ex-Manchester United and England defender Gary Neville also entered the debate on social media.
"Getting to the business end!" he wrote on Twitter. "Jose lobbing grenades out! Anyone going to take him on?"
Chelsea, preparing for Saturday's FA Cup fifth-round tie against Manchester City, host Arsenal on 22 March in a match likely to have a significant bearing on the title fight.
Mourinho has previously said his side are not contenders, describing the Blues as a "little horse" in the Premier League race.
Brendan Rodgers, manager of fourth-placed Liverpool, continued that analogy on Thursday by saying his side "may be the chihuahuas that run in between the legs of the horses" as they look to make a late challenge.
Wenger insisted the title was "Chelsea's to lose" but said Arsenal would "give everything" to win it.
"Many teams are in it and it will be very tight until the end," said the Frenchman, who became Gunners boss in 1996. "We will absolutely give everything and if we don't do I will take responsibility for it."