Lukaku spent last season on loan at West Brom, scoring 17 goals in 35 Premier League appearances for Steve Clarke's men.
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The 20-year-old will now compete with Torres and Ba for a starting berth in Jose Mourinho's side, and came off the bench in Chelsea's 2-0 Premier League win over Hull City on Sunday.
And he is excited about the competition for places that will follow throughout the course of the season.
"It was something I'd been looking forward to for a long time, and hopefully in the next game I'll be able to play a bit more," Lukaku told Chelsea's official website.
"They are world-class players, I get along very well with both of them so it's good to have competition for places."
Lukaku enjoyed a breakout season for West Brom last term, helping them to eighth on the final Premier League table.
And the Belgium international is determined to keep improving under Mourinho this campaign.
"I enjoyed my time at West Brom last season but now I want to move on, become a better player and score more goals, so it's good for me to be competing against Fernando and Demba," he added.
"As a younger player, I'm able to learn from them, which is obviously a good thing, but at the end of the day you have to go out there and do it yourself."