Newcastle are short of defensive cover with just Fabricio Coloccini and Steven Taylor available as senior professionals at centre-back, while Danny Simpson has filled in, along with Thomas Kadar and Ben Tozer in reserve.
Matt Taylor's free-kick rebounded off the bar and eventually fell at the feet of Danny Simpson, whose clearance bounced off a Bolton player and into the path of Lee in the box who calmly slipped the ball past Krul.