LOOKING AHEAD

Boston at Houston, Tuesday, 5:30 p.m. PST,

Celtics officials don’t expect anything like last season’s 29-3 start but couldn’t have been enchanted to see the defending champions torn apart by the Pacers, who beat them, 95-79, in Indianapolis on Saturday night.

A tougher test awaits in this second stop of the Celtics’ three-game trip, against the Rockets, who added Ron Artest and Brent Barry to a 55-win team.

Yao Ming scored 51 points in their first two games and Artest had 45. Whether the big two can become three depends on Tracy McGrady, still plagued by injuries.

The Celtics still have that suffocating defense -- after holding the first two opponents to 36%, Indiana shot just 42% -- but their lack of depth is alarming. With last season’s best reserve, James Posey, in New Orleans, it’s basically the starters, Tony Allen and Leon Powe against the world.