The ex-Spain left-back, winner of three league titles and the Copa del Rey twice in his playing days at Barca, was on Monday installed as successor to Juan Ignacio Martinez at the relegation-threatened Andalusian club until the end of the season.
Sergi, who began his coaching career at Barca, takes charge of a side languishing in the relegation zone after a run of seven matches without a win.
While Almeria wonder where their next victory is coming from, Barca have won all but one of their last 20 games and are in the hunt to win the treble in Luis Enrique's first season at the helm.
He said: "Playing with Pique is very simple; he's outstanding. It's amazing to play with him."
He added: "It was important to start well after the break, and at Celta we knew it wouldn't be easy.
"In the first half we couldn't find any outlets and they were better. In the second half we figured it out and were much better.
"These three points are very important because there are fewer and fewer matches left until the end of La Liga.
"The coming week is very difficult. We have a tough schedule but we can't complain. We're alive in the Champions League, we lead the league and we're in the Spanish Cup final."
