BOSTON - There are two ways to look at the Celtics as they arrive in Philadelphia looking to take one, if not two, games from the Sixers in their best-of-seven playoff series.

Deadlocked one game apiece after a pair of games that were decided by a combined two points, the favored Celtics could easily be leading two games to none or down two games to none.

They won the series opener, overcoming a sluggish start to rally from a 10-point, fourth-quarter deficit on the strength of big-time performances from Kevin Garnett and Rajon Rondo.

But those performances never came in Monday's 82-81 loss to the Sixers. Late in the game it was the Sixers, with their substantially less experienced roster, making plays and hitting crucial free throws late in the game.

Faced with needing to win on the road to regain the home court advantage, the veteran Celtics, losers of both regular-season games at the Wells Fargo Center, say they aren't intimidated by the change in venues.

"I don't really worry about where we play," guard Ray Allen said following Tuesday's loss. "It's just about how we play and when we play them. We will look at film [Tuesday], and we will see everything we didn't do well offensively. I think our defense wasn't too bad. Being in their building down there really isn't going to affect us. It's all about how we play them when we get out there, how we take care and work together better than what we did tonight."

A good sign for the Celtics is that Allen, who missed 20 games this season mostly due to a sore right ankle, is beginning to round his way back into playing shape. Allen's team-high 17 points in 37 minutes Monday was a bright spot for the Celtics.

But in seeing the Sixers end Boston's nine-game home winning streak, there are some concerns for the Celtics.

The Celtics have been able to count on small forward Paul Pierce for years. However, Pierce was a no-show in Monday's game. With Andre Iguodala draped all over him, Pierce, 34 and slowed by an achy knee, hurt the Celtics more than he helped them, finishing with seven points and five turnovers. Iguodala held him scoreless in the fourth quarter.

And the Boston offense was spotty at best in Game 2. After racing out to a 9-0 lead at the start, the Celtics scored just 11 points in the crucial third quarter on 4-for-17 shooting (23.5 percent).

Like Allen, Pierce is not concerned about what has happened but focused on getting better results in Philadelphia in Games 3 and 4.

"It is what it is. I can't change it," Pierce said. "We got our work cut out for us. They took the home court advantage now. We got to try to find a way to get one or two wins in Philly."

While the Sixers were aided by injuries to key players Derrick Rose and Joakim Noah in their first-round series victory over Chicago, it's clear that that the Celtics don't see the Sixers as just happy to be playing this late in the postseason.

"They are a tough defensive team. They grind it out defensively. They try the fastbreak, and they're not going to give in," Pierce said. "They have a good coach over there who instills his mentality into his players, so nothing is surprising. They are what we expected them to be."

Contact John N. Mitchell at jmitchell@philly.com. Follow him on Twitter @JmitchInquirer