Frank Lampard fears he may have a mole among the Chelsea ranks after Tottenham boss Jose Mourinho correctly predicted how the hosts would line up at Stamford Bridge on Saturday.
Mourinho said the Blues would play with a back three and they did just that, doing so to great effect as Lampard oversaw a 2-1 victory to tighten their grip on fourth spot in the Premier League.
With Mourinho having enjoyed two successful spells at the Bridge, Lampard raised the possibility the Portuguese had been tipped off about Chelsea's formation.
"That's the world we live in," he said, having become the first manager to complete a league double over Mourinho in a single league season.
"I am not being sinister about it, but it is the world we live in. When someone has worked at the club previously, I think that can happen.
"When you have been working on a back three for two or three days, I am not that trusting always in terms of everybody but that's life."
Spurs lined up to match their opponents' shape but Chelsea were much the better side, with efforts from Olivier Giroud and Marcos Alonso ensuring Antonio Rudiger's late own goal counted for little.
Lampard allowed his players to take all of the credit, rather than citing his tactics, insisting he did not outwit his former mentor.
"I wouldn't say tactically outwitted because he matched us up," he said.
"Maybe that's a bit of credit because he [Mourinho] knew we played it well at Tottenham. Then it is up to the players, so we have got some previous of playing the system.
"The system only works if the players play it the way they play. The system only works if Ross [Barkley] and Mason Mount are so mobile around Oli [Giroud] up front and get in behind them.
"The system only works if our back three don't sit off and allow people to turn on the ball because they are playing with two kind of false strikers. So it is the players that enforce it. We work on it but the players make the system."