The Brazilian was delighted with his side's 2-0 win at the Etihad Stadium but has insisted that the job remains half done
The Blaugrana claimed a 2-0 win over Manuel Pellegrini's side in England on Tuesday to take a stranglehold in the two-legged contest.
However, the Brazilian, who scored his side's second goal, has insisted that they must not rest on their laurels when they entertain City at Camp Nou.
"We still have the second leg and we have to kill off the tie at home," he told the club's official website.
"A lot can happen in 90 minutes, but we have an important advantage."
Alves also hailed his side's measured performance at the Etihad Stadium, praising the way they dominated possession to counter City's threat.
"We knew that it was going to be a tough match, very hard, because the rival we were going up against are very intense.
"We had to have possession and be a difficult side to deal with for them."