The Argentine forward raced to his team's rescue once again with two goals in the latter stages of the game to clinch all three points for the hosts
Lionel Messi was once again the difference for the Catalans, scoring twice in the last 18 minutes to reverse a 2-1 deficit and give his side an early lead atop the Group G standings.
Cristian Tello opened the scoring after 14 minutes, but the home side was pegged back just before the half-hour mark by an own goal from Dani Alves from a Spartak break.
Barca struggled to create many opportunities, and was carved apart on the break once more in the second half as Romulo stunned the home crowd into silence when he gave the visitors a shock lead in the 59th minute.
But Messi popped up with two close-range strikes in the 72nd and 80th minutes to put the Catalans back in the lead for good, though question marks remain after they were given a run for their money by the determined side from Russia.
Tito Vilanova opted for Cesc Fabregas in midfield, while Adriano filled in at left back in the absence of regular starter Jordi Alba.
Tello was also handed a chance to impress with a start in the Barca front three, and he grabbed the opportunity with both hands with the opening goal after 14 minutes.
The 21-year-old beat his marker by cutting in off the left flank, and with Spartak’s defense slow to react, he had time to pick his spot and drill low into the far corner.
The goal came as a welcome boost for Barca, which had seen defender Gerard Pique forced off moments earlier through injury, with summer signing Alex Song coming on in his stead.
Messi nearly doubled the advantage in the 20th minute when he turned to face goal at the top of the box, but a wicked effort curled past the post by inches.
The Argentine would soon rue that miss, thanks to a catastrophic defensive sequence that saw Spartak, which had barely had a kick up until that point, stun Camp Nou by drawing level.
Emenike did the hard work, racing past Javier Mascherano on the left before sliding a cross towards goal. The ball was missed completely by Song, and Alves, under no pressure, inexplicably side-footed into the corner of his own goal.
Barca, despite dominating possession, found it hard to find a route through to goal in the face of a determined rearguard effort from the Russian side, but it managed to give the away side a few scares in the closing stages of the first half.
Fabregas thought he had made a breakthrough in the 37th minute when he lifted Xavi’s clipped pass towards goal with his head, but Andriy Dykan was alert to prevent it from sneaking in under the crossbar.
The Spain midfielder saw an appeal for a penalty go unacknowledged moments later after a tussle with Marek Suchy, before Xavi drove just off target with one of the last kicks of the half.
Alves nearly made amends for his first-half mishap moments after the restart with an arrowed drive into the top corner, but his goal was correctly chalked off after he had strayed inches offside.
Spartak was soon able to break towards the Barca goal, but Emenike could not make the most of Ari’s cutback, and fired over the bar from the edge of the box.
The visitors would make no such mistake with their next counterattack though, and stormed into the lead in the 59th minute, just seconds after coming mightily close to conceding.
Messi was denied from point-blank range by a great save from Dykan, and Spartak stormed straight down the pitch. Ari led the charge down the left and teed up Adien McGeady at the top of the box, whose clever slipped pass allowed Romulo to skip past Adriano and slot neatly under Victor Valdes.
But Barca would not be down for long. Tello was the architect, wriggling past two defenders on the left flank before cutting back to Messi from the byline, who made no mistake in front of an open net.
Suddenly, Camp Nou was back in full voice as Barcelona, with its tail up, found itself with 18 minutes to find a goal to give the club all three points.
Substitute David Villa nearly achieved that objective when he faced an unguarded net after a scramble from a cross, but Rafael Carioca produced a superb block to deny the Spain striker.
But Messi, once again, would step up to answer the call, and arrived at the far post to head home an Alexis Sanchez’s cross with authority to put the hosts in front.
Sanchez fashioned a similar opportunity moments later for Pedro, but he could not match Messi’s exploits as he sliced across the face of goal from a good position.
Barca played out the closing minutes with ease, as Spartak, worn out from tireless defending all game, simply had nothing left to respond.