It seemed as though every shot the Thunder took was contested defensively.
"We showed bodies. We showed hands," Celtics forward Kevin Garnett said. "Durant got loose in the second half, but we played defense for 48 minutes."
Russell Westbrook had 16 points (15 in the second half), 10 assists, four steals and two blocked shots, but also had eight turnovers.
Serge Ibaka filled in for starter Jeff Green, who suffered a sprained ankle at Saturday's practice and is listed day-to-day after missing his first start since March 2009. Ibaka had a game-high 11 rebounds and eight points.
Ray Allen led Boston with 19 points, Paul Pierce scored 17 and point guard Rajon Rondo had 10 points and 10 assists.
"They're a title-contending team," Brooks said of the Celtics. "In order for us to play against elite teams, we really have to play good basketball for 48 minutes."
Brooks considered it another lesson learned, and it was not due to a lack of trying.
"Playing against the Celtics, they make you look at yourself in different ways because they challenge you in so many ways," Brooks said. "They're a physical team, they're smart, they're aggressive. They know how to play, but they've played a lot of basketball. We want to get there one day."