The 22-year-old Carlsen, hailed by Russian legend Garry Kasparov as a Harry Potter-type "super-talent", has built up an almost unassailable lead in the one-sided series after three victories and six draws.
Wearing a black jacket and playing with the white pieces, the part-time fashion model faced a tense-looking Anand who needs three straight victories to save his world champion title which he has held since 2007.
The duo are playing in Anand's hometown of Chennai at a table set in front of a glass screen from behind which photographers were allowed to briefly take pictures before police asked them to leave. The ensuing commotion briefly interrupted proceedings.
Anand, who at 43 is 21 years older than his rival, had conceded before the start at 3 pm (0930 GMT) on Friday that it will take a miraculous turnaround to keep his chances alive.
"I can try but the situation does not look very good," he said on Thursday as experts predicted a short game, which appeared likely after an aggressive series of moves at the start.
Carlsen, the current world number one, has been on supreme form in the 12-game world duel, the only tough challenge from the Indian coming in
Thursday's ninth game which lasted three hours and 21 minutes.
Visibly relieved at emerging unscathed from the keenly fought contest, Carlsen did not respond when asked by reporters if the crown was now virtually in the bag.
"This was a very difficult game," Carlsen said. "The positions were complicated. I had to find the right moves to regain balance. There was a fear
of being mated all the time."
British grandmaster Nigel Short tweeted "end of an era" even before the match had ended, adding that Friday would be "the only day I would not
begrudge them a quick draw."
If he takes the title, Carlsen will miss by a few weeks becoming the youngest world champion, a record set by his one-time coach Kasparov in 1985.
Polgar told AFP that Carlsen's approach had been "refreshingly new" and aggressive, which had bamboozled his far more experienced opponent.
"In the first eight games of this championship match, he forced his game plan onto Anand," Polgar said. "In chess, positioning and strategy is crucial and unless the development of one's pieces is going according to one's plan, experience will count for little," she added.
Carlsen has dominated the World Chess Federation's list of top players in the last three years, with a top rating of 2,870 points that broke Kasparov's best of 2,851 points achieved in 1999.
Introduced to chess by his father, Carlsen showed off his genius as a toddler. At the age of two, the self-taught prodigy knew by heart all the major car brands and later memorised the long list of Norway's municipalities, with their flags and administrative centres.
Sibling rivalry with one of his older sisters sparked his interest in chess, which soon led to his first competition at the age of eight.
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The breakthrough came in 2004, when the 13-year-old defeated Russian former world champion Anatoly Karpov.
A fashion model in his spare time, Carlsen made it to the Time magazine list of the 100 most influential people in the world in 2013. He also won the Chess Oscars, awarded by Russian chess magazine '64' to the world's best player, for four consecutive years from 2009 to 2012.
Carlsen revealed his single-minded approach in August when he and his team visited Chennai to check out the facilities in the southern coastal metropolis.
Worried he may fall sick in India during the title bout, Carlsen's team forced organisers to insert an "illness" clause in the contract by which a player can take a two-day break if he becomes sick.
All India Chess Federation secretary V. Hariharan said it was the first time an illness clause had been included for a world championship match.
The total prize fund for the title clash is about $2.24 million with the winner getting 60 percent and the loser taking home the rest.