The last time they visited the nation’s capital, all the Celtics could focus on was being on the same stage with President Bush.

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Wednesday afternoon, as they boarded a plane for D.C. again, their focus was quite different.

The Celtics are 20-2 and once again on top of the NBA world. But listen to them at practice and they realize that they are the only people who can keep them there.

“It’s not hard at all, especially when you’re ultimate goal is to win a championship, the focus is there everyday,” Paul Pierce said. “Just because we’re veterans, we don’t have any letdowns. We check everybody, we check on one another and when we see one guy have slippage, we pick them up. That’s what this team is all about.”

Pierce added that the Celtics have a very good system of checks and balances on each other to keep the focus where it needs to be.

Coach Doc Rivers has found ways to keep his team sharp.

As well as the Celtics know themselves, the Wizards are wondering who they are. They completed a stunning comeback on Tuesday night, coming from 15 points down to beat the Detroit Pistons going away. But still, at 4-15, the Wizards are a mess. Coaching journeyman Ed Tapscott took over for Eddie Jordan following the team’s 1-10 start without the injured Gilbert Arenas available.

In an effort to get more scoring depth, the Wizards pulled off a three-way trade on Wednesday, a deal that should have former Celtic Mike James available for Thursday’s contest.

If the Celtics can handle Caron Butler, they stand a very good chance of improving to 21-2 with the James Posey-Chris Paul-led Hornets up next on Friday at the Garden.