The Oilers Twitter account today announced that Lennart Petrell was back in the lineup and Teemu Hartikainen has been placed on Injured Reserve:

#Oilers forward Lennart Petrell has been activated from the IR and forward Teemu Hartikainen has been placed on injured reserve

— Edmonton Oilers (@EdmontonOilers) February 25, 2013

Petrell recovered from a concussion due to a puck to the head during warm-ups against Colorado, while Hartikainen's injury has not been announced.

Hartikainen did suffer soreness in his shoulder after being hit last Saturday against Colorado. He played just 8:33 and didn't return. But Hartikainen skated in practice the next day and didn't miss any time due to injury. In fact, Hartikainen contributed the game-tying power play goal in Edmonton against Phoenix on Saturday, a goal which sent the game into overtime, where the Oilers eventually won in a shootout.

Petrell will skate on the fourth line with Nail Yakupov and Chris Vandevelde.