Rangers' young guns breathed new life into their side's Champions League hopes and Alex McLeish's job prospects with a draw against the odds in Oporto.
Lisandro looked to have sent Porto into second place in Group H with a fine glancing header from a Bosingwa cross.
Rangers had failed to put a shot on target until Chris Burke headed into the path of fellow young substitute Ross McCormack to drive the ball home.
And they held on despite late pressure to stay ahead of Porto and Artmedia.
Inter Milan's defeat of the Bratislavans means that Rangers are guaranteed at least a place in the Uefa Cup for finishing third.
But the Glasgow side's hopes of becoming the first from Scotland to progress to the knockout stages had been hampered by poor form that has put McLeish on the brink of losing his job.
They were also not helped by injury to the talismanic Dado Prso and a clutch of other strikers.
Veteran Alex Rae returned to the midfield for the first time since August, with striker Steven Thompson dropping to the bench and Fernando Ricksen moving to right-back in place of Alan Hutton.
Porto dominated from the start and Ricardo Quaresma unleashing an angled shot into the arms of goalkeeper Ronald Waterreus from the edge of the box.
Bosingwa whipped a dangerous cross into the box only for Lisandro to send his header just over the crossbar under pressure from Marvin Andrews.
Quaresma jinked between Ricksen and Hamed Namouchi but fired into the side netting when a cross would have been the better option.
Porto were being held at bay by the negative tactics of Rangers, who themselves had struggled to progress beyond the halfway line.
And frustrated Porto coach Co Adriaanse sent on striker Hugo Almeida at half time in place of Pedro Emanuel.
Almeida and Jorginho both threatened before Porto's pressure eventually told.
Lisandro beat Ricksen in the air to glance home the opener from Bosingwa's cross from deep after 60 minutes.
Captain Barry Ferguson squandered a rare Rangers chance, firing well over from 20 yards following a Ricksen cross.
But McLeish sent on Burke and McCormack and they combined for a smash and grab equaliser finished from 10 yards.
Porto pressed forward and Rangers goalkeeper Ronald Waterreus produced a superb double save, pushing the ball against the outside of the post after a last-ditch goalmouth scramble.
Porto: Vitor Baia, Cesar Peixoto, Pepe, Pedro Emanuel (Hugo Almeida 45), Bosingwa, Diego (Bruno Alves 64), Paulo Assuncao, Gonzalez, Quaresma, Lopez, Jorginho.
Subs Not Used: Helton, Ricardo Costa, Ibson, McCarthy, Ivanildo.
Goal: Lopez 60.
Rangers: Waterreus, Murray, Kyrgiakos, Andrews, Ricksen, Lovenkrands (Burke 78), Ferguson, Hemdani, Alex Rae (Thompson 62), Namouchi, Jeffers (McCormack 76).
Subs Not Used: Klos, Malcolm, Pierre-Fanfan, Hutton.
Booked: Hemdani, Murray, Ferguson.
Goal: McCormack 83.
Ref: Herbert Fandel (Germany)