The Villa boss preferred to start new signing Christian Benteke against West Brom and Tottenham ahead of the club’s record signing, even though Bent has already notched three goals in six starts so far this season.
But Lambert insists talk of a fractious relationship is wide of the mark, claiming Bent’s disappointment at not starting is instead a positive feature of the 28-year-old’s persona.
"I've never had a problem with Darren. I have a laugh and a joke with him,” Lambert told reporters.
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"But he has not been knocking on my door. There was never a problem.
"You wouldn't take Darren's selfishness away from him because he is a goalscorer and that's what he does best.
"As for people saying we are not talking, I don't worry because I know it's not true. Like I said, we have a laugh and a joke and there has never been that problem.”
Lambert also believes that, while keeping his dressing room happy is a necessity, his main job is to pick a winning side.
"I try to be fair and honest with everyone," he added. "I don't rule with fear if that is what people think. I treat people the right way and respect them. I don't do anything untoward."
"But my job is to pick a team that will win us a game. That is my job and that's what I try and do for this football club.
"It will be the same for everyone. I trust the lads to perform. That's the great thing I've got but I can't keep everyone happy all the time. It's a decision I'll make."
Villa travel to face Fulham this Saturday, and Lambert believes it is exactly this need to pick a winning team that has seen Belgian front man Benteke get the nod ahead of Bent.
Lambert added: "I'm pretty sure when he [Benteke] went away after the Tottenham game [which Villa lost 2-0], when he had a big chance to score, he could have gone under.
"To bounce back with two goals in two games for his national team is excellent. That's a big thing for a young player, to get over the disappointment.
"Christian is playing in a right top Belgium side and more than holding his own.
"For someone who is only 21 and the way he is performing, what he will do for this club will be terrific.
"I thought that when we signed him 'this kid can be a right top player'. I think he can be huge, anything he wants to be. He can be a top, top striker because he is a handful.
"He will make mistakes because he doesn't know everything about the game but as time goes on, and he becomes experienced, he will be an absolute handful."