Senegal international Ba completed his £7million switch to Stamford Bridge from Premier League rivals Newcastle on Friday and is in contention to make his debut in the FA Cup third round clash with Southampton on Saturday afternoon.
Torres has already clocked up 32 appearances for the Blues this term due the shortage of options up front for the Premier League side, a situation which was exacerbated by the sale of Daniel Sturridge to Liverpool.
Benitez is confident the Spain international will welcome the increased competition for places, particularly after voicing his opinion that new faces were needed in conversation with his compatriot.
He said: "Fernando is happy to see good players signing because it means we can win more games.
"I was talking with him in the last couple of weeks and he said we needed more bodies. We know he is playing too many games but we couldn't rotate him like we could with other areas of the squad because we did not have many options in attack.
"With Daniel Sturridge leaving, having Fernando as the only main striker was always a problem.
"So Demba is a good option for us because I can manage both strikers and hopefully it will good for both of them.
"It is one thing if Torres needs it, but it's good for the team to have players competing for their places because you can keep everyone on their toes."
And Benitez has played down suggestions that Chelsea have taken a gamble on their move for Ba, with concerns previously raised over the long-term fitness of the former West Ham and Hoffenheim man.
He said: "There is no risk with Ba. He was playing every game for Newcastle and if he could do that it means he is fit and available. We'll try to manage the situation but he can play for us. He is fine."
The Blues boss added: "We were looking for a player who can play right now because we have a game every three days and can't be waiting for someone who will take three months to settle into the Premier League.
"He scores goals, he can hold the ball up, he can pass, he is good in the air and his movement is good.
"He has everything you are looking for in a striker and at Newcastle he showed he can also play as a second striker behind Papiss Cisse.
"He can even play out wide but when we have Mata, Hazard, Oscar and Moses, why do I need to use Ba as a winger? He is a striker and we've bought him to compete with Fernando."