The Brazilian saved the day for the Catalan giants 19 minutes from time with a wonderful finish from Andres Iniesta's exquisite pass.
It came after Atletico substitute Diego had silence the home support with a sensational opener when he crashed a thunderous 25-yarder into the near post top corner from just outside the right of the area.
The hosts dominated possession but struggled to carve out clear-cut chances as the visitors illustrated just why they shared the mantle of the competition's best defence prior to kick off.
And it could have been even worse for the hosts if ex-Barcelona favourite, David Villa - who missed an early sitter - had brought his shooting boots.
Both sides also suffered major injury setbacks as both Gerard Pique and Diego Costa hobbled off. But the real story was the quality of both goals as Atletico secured a fourth straight draw with the Catalans to set up what promises to be an intriguing second leg at the Vicente Calderon.
PRE-MATCH: Iniesta returns, Costa starts - Andres Iniesta comes back into the tried and tested Barca line-up after featuring as a substitute against Espanyol at the weekend, as Martino springs no surprises. The same can't be said for Simeone, who includes his main man, Costa from the start despite suggesting he wouldn't feature due to injury. Ex-Barca striker David Villa is also in the visitors' side in place of the suspended Raul Garcia.
5' - CHANCE FOR ATLETICO! Pinto's hurried clearance goes straight to an Arda Turan deep in Barca territory. It's flicked inside to Villa who slides a shot inches past the post from eight yards out. He should have scored. Let off for the home team's keeper.
13' - INJURY. Pique is forced off after landing awkwardly following an aerial challenge with Costa.
26' - GREAT BLOCK! Messi skips beyond his man and teases a pass into Iniesta who looks all set to open the scoring, only to be denied by a sensational last-ditch block by Diego Godin.
28' - HUGE BLOW FOR ATLETICO. Costa is clutching his hamstring and Simeone shuffles his hands to suggest they'll need to make a change. The 33-goal hitman will depart for Diego.
45+2' - GREAT SAVE! A quickly taken free kick catches Barca napping and Villa seizes upon it, wriggles inside and drills in a shot that Pinto tips to safety.
56' - GOAL: Barcelona 0-1 Atletico Madrid: Wow! Atletico silence the Camp Nou as Diego unleashes a quite sensational shot from the far right that arrows into the near post top corner from 25 yards.
64' - SUPERB EFFORT! Busquets lets fly with a 30-yard volley that Courtois is forced to tip around the post.
71' GOAL: Barcelona 1-1 Atletico Madrid. Iniesta finally splits the Atletico defence with a sublime ball in behind three defenders, allowing Neymar to race onto it on the far left of the area and curve a stunning finish beyond the keeper. All square.
75' - GREAT SAVE! Courtois flings himself to his left to keep out a belter from Iniesta that was searing into the corner. Wonderful goalkeeping.
86' - ANOTHER FINE SAVE! Messi curls the free kick over the wall and towards the corner but Courtois is there once again to tip it away.
Atletico Madrid have won seven, drawn two and lost none of their nine matches in the Champions League so far this season – no side has won more CL games this season.
This was Barcelona's 500th match in European competition, making them the first team to reach that landmark.
Thibaut Courtois made five saves against Barcelona, his best record in a Champions League game
Neymar has scored four goals in the Champions League this season, the same as Ronaldinho in his first campaign for Barcelona
(Stats from Opta)
TALKING POINT: Can Atletico keep challenging without Costa? Costa's namesake, Diego ensured it didn't matter in the first leg courtesy of that wonder strike, but with Atletico's 33-goal talisman hobbling off with what looked like a hamstring injury, Simeone's gamble on his striker's fitness could backfire in the weeks ahead as they continue to fight for honours on two fronts.
MAN OF THE MATCH
Thibaut Courtois (Atletico Madrid): The Giant stopper had little to do in the early stages but as Barcelona laid siege to the Atletico goal late on, he produced three world class saves to secure a hard-fought draw for his side.
Barcelona: Pinto 6, Alves 6, Piqué 5, Mascherano 6, Alba 6, Busquets 6, Xavi 6, Cesc 6, Iniesta 7, Neymar 7, Messi 7. Subs: Bartra 7, Sanchez 7.
Atletico Madrid: Courtois 9, Juanfran 7, Godín 8, Miranda 7, Filipe Luis 8, Gabi 7, Tiago 7, Koke 7, Turan 6, Villa 5, Diego Costa 5. Subs: Diego 7, Sosa 6, Rodriguez 5.
MATCH IN A TWEET
- Sports & Recreation
- Atletico Madrid
- Andres Iniesta
- Diego Costa
- David Villa