WALTHAM — Leandro Barbosa  has heard the time-tested expression in basketball over and over: defense wins championships. Now, after nine full seasons in the NBA, the 29-year-old finally is on a team that believes it.
Growing up in Brazil and playing his formative NBA seasons in Phoenix, Barbosa was all about getting to the basket at all costs but the defensive side of his game was admittedly not a priority. When he signed with the Celtics  on Oct. 18, all of that changed.
“It’s different,” Barbosa said after practice on Tuesday. “Especially, for me, I came in late. I’m trying to work really hard to pick things up really quick. I’m happy to be involved, and we’re doing better. Hopefully, next game we’ll do even better.
‘I feel great. I think the most important thing is to feel comfortable. I think I’m feeling that right now. The coaches talk to me in a lot of different ways, in an offensive standpoint and an offensive standpoint. I’m just enjoying it right now.’
Barbosa said the biggest change in his philosophy came from the coaching staff.
‘I think this is the first team that is a defensive team, and I’m happy because I know that I have to definitely be better on the defensive end,” Barbosa said. “From where I come from, we don’t play defense, and I’m talking about Brazil. So, we’re getting better. I’m very happy and getting myself better.
‘What I learned, when you play defense, everything comes automatic. Especially, on this team we have so many weapons, I don’t think we don’t have to worry about offense. To go to the championship, we have to play better defense. That’s what we’re looking for and what we’re working for.’