Ronaldo, hoping to end Messi's three-year run as World Player of the Year, thrilled the Bernabeu when he snatched a 90th-minute winner in Real Madrid's 3-2 victory over Manchester City in Group D on Tuesday.
Messi not only netted Barca's 71st-minute equaliser against the unfancied Russians at the Nou Camp, but also grabbed the winner with a rare header 10 minutes from time.
The Argentina international has been top scorer in Europe's elite club competition the past four seasons and his latest double took his Champions League goal tally to 53 in 69 appearances while Ronaldo has 39 in 81 matches.
"We deserved to win but it was a really tough game," Messi told Spanish television.
"It's not easy when they defend so deep and you can't find the spaces," added the 25-year-old, who has now scored 109 goals in his last 100 official matches for Barca.
"They were comfortable defending in their penalty area and they have very strong and quick forwards and can break quickly.
"Things got complicated but we kept pressing and we managed to turn it around."
HOME-GROWN SUCCESS
Messi has so often stepped up at crucial moments to save Barca and he was again decisive after they found themselves 2-1 down in the 59th minute.
Spartak were looking to catch the four-times European champions on the break and, after a Messi effort was well saved by Andriy Dykan, they raced up the other end and Brazilian midfielder Romulo finished low past Victor Valdes.
The match had appeared to be going Barca's way when B team youngster Cristian Tello struck to make it 1-0 in the 14th minute but Spartak were level a quarter of an hour later when Daniel Alves turned the ball into his own net.
The visitors' ultra-defensive tactics frustrated Barca and they were flirting with a first home defeat in 17 European outings since falling 2-1 to another Russian side, Rubin Kazan, in October 2009.
However, Tello created the equaliser 19 minutes from time when he pulled the ball back from the byline for Messi to tap in before substitute Alexis Sanchez floated a perfect cross over and Messi nodded past Dykan.
It was an impressive comeback from the La Liga side, bidding for a third European crown in five years, and ensured a winning debut in the competition for new coach Tito Vilanova, who stepped up to replace Pep Guardiola at the end of last season.
It was also another home-grown success for the Catalan club, with Vilanova fielding eight academy graduates in his starting line-up including Messi, Xavi, Cesc Fabregas and Tello.
REAL THORN
Barca's fightback ensured Spartak's Spanish coach Unai Emery, a former boss at La Liga sides Almeria and Valencia, is still seeking his first win against Barca after 13 attempts.
"I have had the poor luck never to have beaten Barca but every time I come here I try to win," Emery told a news conference. "It's not impossible and it's be
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