Boston ? Boston Celtics forward Paul Pierce has an injury in his left foot that will keep him out for two to three weeks.

Pierce has a stress reaction – a swelling of the bone and the soft tissue surrounding it, team spokesman Jeff Twiss said Thursday. Pierce will miss tonight’s game against Philadelphia and the five-game road trip that starts Tuesday in Denver.

“I’m not sure if he’s going to accompany the team, but he will not play on the road trip,” Twiss said.

Pierce said his foot started hurting after Saturday’s game in Charlotte.

He felt pain again after Wednesday night’s 96-95 loss to Golden State, in which he scored 27 points, and had an MRI on Thursday morning.

The Celtics are already without guard Wally Szczerbiak, who has a sprained right ankle and could return for the road trip. Forward Brian Scalabrine missed the Warriors game because of the flu.