A late header from Christian Benteke, who has replaced Bent as the number one striker, moved Aston Villa out of the English Premier League relegation zone.
But the £18 million striker failed to feature even among the substitutes, with Lambert favouring rookie Jordan Bowery instead.
Lambert denied there was any fallout with Bent or that the striker had left the stadium before kick-off after his exclusion from his plans.
Lambert said: "Darren was in the squad, it was the same on Saturday. I just picked the same group. I do what think is best for Aston Villa.
"But honestly, I don't have a problem with Darren Bent and I do rate him as a player.
"I've no problem with his attitude in training, none whatsoever.
"Did he storm off? No, not a thing. I would tell you. I thought he was fine. I read the team out. The most important thing is Aston Villa.
"Will I listen to offers in January? Honestly my main concern is winning games for this club, nothing else.
"Can Bent play again for us Yes, never rule anything out. But I pick a team to win, I never pick one I think will lose."
The game between the two struggling sides looked to be heading towards stalemate, although Villa had offered the greater number of chances.
However, with 10 minutes left Benteke settled the issue, the Belgian forward rising about Reading's defence to head downwards past goalkeeper Adam Federichi.
The result was just the third win of the season for Aston Villa, who fielded eight players under the age of 23, and Lambert admitted afterwards it was a significant one.
"We knew the Arsenal game at the weekend would take a lot out of us," he said.
"Reading had also played well against Wigan so knew it would be a tough game.
"But I don't know about it being a six-pointer. Never look at things now, look in May."
Reading boss Brian McDermott was left to bemoan his side's defending when Benteke headed home an Ashley Westwood corner 10 minutes from time.
It was another late and crucial goal conceded by Reading, who lost 3-2 at Wigan.
He said: "I thought we were going to get a point. I knew the first goal was going to be crucial.
"I thought the shape of the team was good but to lose the goal from a set piece was disappointing.
"I thought we had solved the late goal problem.
"But it's not a six-pointer. It's a game of football and we've got a game of football to look forward to against Manchester United at the weekend."
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