The Manchester United boss delivered a damning verdict on the Blues' championship chances on Friday, claiming: "You look at teams with a chance of winning the league and I'd put Everton above Chelsea as they have more about them.
"Maybe not in terms of natural ability, but in their enthusiasm and energy and structure of the team."
Ferguson's harsh words have not gone down well in west London, where Chelsea swept aside Birmingham and could easily have doubled their 3-0 victory scoreline.
Now Petit has outlined his plan to mount a genuine title bid, taking advantage of United, Arsenal and Liverpool's preoccupation with the Champions League.
French midfielder Petit, 32, said: "Sir Alex Ferguson will say what he wants, but the fact is a lot of people weren't confident about Chelsea this season.
"We've been under pressure a lot of times, so now we have to work, work, work and see where we are at the end of the year.
"Our target is to finish as near as possible to the top of the table.
"Europe is over now so we must be focused on the league and both cups.
"Europe is probably a distraction for Arsenal, Liverpool and Manchester United, although they've got more players than us.
"That makes a big difference when you're in the Champions League, as you need a strong, strong squad.
"But we'll try and do it our own way. We have so many players with big technical qualities. And the way to do well is to play with a lot of movement, like we did yesterday."
And Petit insisted his team-mates have identified aspects of their game which they can strengthen further.
"We're on a good run, winning four games from the last five - and we had some very good, wonderful moments yesterday," he added.
"But we're trying to improve game after game and now have to get better when we have the ball, keeping possession for longer when we're winning.
"We have to be focused as anything can happen in the Premiership, like three weeks ago when we lost two games.
"It's been very difficult over the last weeks, so we were happy yesterday, but a bit quiet because we know how hard it's been. Now it's very important to keep the atmosphere high."