The 20-year-old attacker is desperate for his compatriot to sign for the Nerazzurri rather than the Premier League club if he were to depart Sao Paulo this summer
The Nerazzurri appear to be locked in a bidding war with United for the Sao Paulo starlet, as Red Devils boss Sir Alex Ferguson admitted on Monday that he is keen to lure the attacking midfielder to Old Trafford.
However, Coutinho is hoping that Lucas ends up at Appiano Gentile instead.
"He's a fantastic player, a phenomenon," the 20-year-old told Tuttosport. "Should he come, he would help us a lot and I hope he arrives."
For the time being, though, Coutinho is focusing his attentions towards nailing down a regular place in the Inter side after a successful loan spell at Espanyol.
"I have returned from Catalunya stronger," the attacker added. "Playing so many games in a row was fundamental to my growth because it had been so long since I had done that.
"It is important to have self-confidence and feel the support of your environment, but that only comes from playing game after game.
"It makes you feel better and also makes you feel important."
Inter went through two coaches while Coutinho was in Spain, with Gian Piero Gasperini getting the sack early on last season before his replacement, Claudio Ranieri, made way for Andrea Stramaccioni in March.
Consequently, this feels like a new beginning for Coutinho, who freely admits that he is enjoying working under the Nerazzurri's former Primavera boss.
"He talks a lot and not only to me," he said of Stramaccioni. "He is a coach who is open to us all and disposed to speaking with his players.
"The work that he is doing is very important because he is clearly conveying what he wants from us. From me, for example, he asks for even more attention in defensive phases of play."
Coutinho, who already has five Brazil caps to his name, netted the only goal of the game in Inter's Trofeo TIM victory over Juventus at the weekend.